Use CommandType in more places (#12832)

# Description
Kind of a vague title, but this PR does two main things:
1. Rather than overriding functions like `Command::is_parser_keyword`,
this PR instead changes commands to override `Command::command_type`.
The `CommandType` returned by `Command::command_type` is then used to
automatically determine whether `Command::is_parser_keyword` and the
other `is_{type}` functions should return true. These changes allow us
to remove the `CommandType::Other` case and should also guarantee than
only one of the `is_{type}` functions on `Command` will return true.
2. Uses the new, reworked `Command::command_type` function in the `scope
commands` and `which` commands.


# User-Facing Changes
- Breaking change for `scope commands`: multiple columns (`is_builtin`,
`is_keyword`, `is_plugin`, etc.) have been merged into the `type`
column.
- Breaking change: the `which` command can now report `plugin` or
`keyword` instead of `built-in` in the `type` column. It may also now
report `external` instead of `custom` in the `type` column for known
`extern`s.

crates/nu-cmd-lang/src/core_commands/alias.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Alias;
@@ -29,8 +30,8 @@ impl Command for Alias {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-cmd-lang/src/core_commands/const_.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Const;
@@ -30,8 +31,8 @@ impl Command for Const {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-cmd-lang/src/core_commands/def.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Def;
@@ -28,8 +29,8 @@ impl Command for Def {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/export.rs

@@ -1,4 +1,5 @@
 use nu_engine::{command_prelude::*, get_full_help};
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct ExportCommand;
@@ -23,8 +24,8 @@ impl Command for ExportCommand {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(
@@ -40,7 +41,7 @@ impl Command for ExportCommand {
                 &ExportCommand.examples(),
                 engine_state,
                 stack,
-                self.is_parser_keyword(),
+                self.is_keyword(),
             ),
             call.head,
         )

crates/nu-cmd-lang/src/core_commands/export_alias.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct ExportAlias;
@@ -29,8 +30,8 @@ impl Command for ExportAlias {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-cmd-lang/src/core_commands/export_const.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct ExportConst;
@@ -30,8 +31,8 @@ impl Command for ExportConst {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/export_def.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct ExportDef;
@@ -28,8 +29,8 @@ impl Command for ExportDef {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/export_extern.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct ExportExtern;
@@ -25,8 +26,8 @@ impl Command for ExportExtern {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/export_module.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct ExportModule;
@@ -30,8 +31,8 @@ impl Command for ExportModule {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/export_use.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct ExportUse;
@@ -29,8 +30,8 @@ impl Command for ExportUse {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/extern_.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Extern;
@@ -25,8 +26,8 @@ impl Command for Extern {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/for_.rs

@@ -1,4 +1,5 @@
 use nu_engine::{command_prelude::*, get_eval_block, get_eval_expression};
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct For;
@@ -41,8 +42,8 @@ impl Command for For {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/hide.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Hide;
@@ -31,8 +32,8 @@ This command is a parser keyword. For details, check:
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/let_.rs

@@ -1,4 +1,5 @@
 use nu_engine::{command_prelude::*, get_eval_block};
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Let;
@@ -30,8 +31,8 @@ impl Command for Let {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-cmd-lang/src/core_commands/module.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Module;
@@ -30,8 +31,8 @@ impl Command for Module {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/mut_.rs

@@ -1,4 +1,5 @@
 use nu_engine::{command_prelude::*, get_eval_block};
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Mut;
@@ -30,8 +31,8 @@ impl Command for Mut {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-cmd-lang/src/core_commands/overlay/command.rs

@@ -1,4 +1,5 @@
 use nu_engine::{command_prelude::*, get_full_help};
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Overlay;
@@ -25,8 +26,8 @@ impl Command for Overlay {
   You must use one of the following subcommands. Using this command as-is will only produce this help message."#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(
@@ -42,7 +43,7 @@ impl Command for Overlay {
                 &[],
                 engine_state,
                 stack,
-                self.is_parser_keyword(),
+                self.is_keyword(),
             ),
             call.head,
         )

crates/nu-cmd-lang/src/core_commands/overlay/hide.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct OverlayHide;
@@ -35,8 +36,8 @@ impl Command for OverlayHide {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/overlay/new.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct OverlayNew;
@@ -33,8 +34,8 @@ This command is a parser keyword. For details, check:
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/overlay/use_.rs

@@ -2,7 +2,7 @@ use nu_engine::{
     command_prelude::*, find_in_dirs_env, get_dirs_var_from_call, get_eval_block, redirect_env,
 };
 use nu_parser::trim_quotes_str;
-use nu_protocol::ast::Expr;
+use nu_protocol::{ast::Expr, engine::CommandType};
 
 use std::path::Path;
 
@@ -50,8 +50,8 @@ impl Command for OverlayUse {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/return_.rs

@@ -1,4 +1,5 @@
 use nu_engine::command_prelude::*;
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Return;
@@ -28,8 +29,8 @@ impl Command for Return {
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(

crates/nu-cmd-lang/src/core_commands/scope/command.rs

@@ -1,4 +1,5 @@
 use nu_engine::{command_prelude::*, get_full_help};
+use nu_protocol::engine::CommandType;
 
 #[derive(Clone)]
 pub struct Scope;
@@ -19,8 +20,8 @@ impl Command for Scope {
         "Commands for getting info about what is in scope."
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(
@@ -36,7 +37,7 @@ impl Command for Scope {
                 &[],
                 engine_state,
                 stack,
-                self.is_parser_keyword(),
+                self.is_keyword(),
             ),
             call.head,
         )

crates/nu-cmd-lang/src/core_commands/use_.rs

@@ -1,7 +1,10 @@
 use nu_engine::{
     command_prelude::*, find_in_dirs_env, get_dirs_var_from_call, get_eval_block, redirect_env,
 };
-use nu_protocol::ast::{Expr, Expression};
+use nu_protocol::{
+    ast::{Expr, Expression},
+    engine::CommandType,
+};
 
 #[derive(Clone)]
 pub struct Use;
@@ -40,8 +43,8 @@ This command is a parser keyword. For details, check:
   https://www.nushell.sh/book/thinking_in_nu.html"#
     }
 
-    fn is_parser_keyword(&self) -> bool {
-        true
+    fn command_type(&self) -> CommandType {
+        CommandType::Keyword
     }
 
     fn run(