Add command_prelude module (#12291)

# Description
When implementing a `Command`, one must also import all the types
present in the function signatures for `Command`. This makes it so that
we often import the same set of types in each command implementation
file. E.g., something like this:
```rust
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
    record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
    ShellError, Signature, Span, Type, Value,
};
```

This PR adds the `nu_engine::command_prelude` module which contains the
necessary and commonly used types to implement a `Command`:
```rust
// command_prelude.rs
pub use crate::CallExt;
pub use nu_protocol::{
    ast::{Call, CellPath},
    engine::{Command, EngineState, Stack},
    record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, IntoSpanned,
    PipelineData, Record, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
};
```

This should reduce the boilerplate needed to implement a command and
also gives us a place to track the breadth of the `Command` API. I tried
to be conservative with what went into the prelude modules, since it
might be hard/annoying to remove items from the prelude in the future.
Let me know if something should be included or excluded.

crates/nu-command/src/date/date_.rs

@@ -1,9 +1,4 @@
-use nu_engine::get_full_help;
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, IntoPipelineData, PipelineData, ShellError, Signature, Type, Value,
-};
+use nu_engine::{command_prelude::*, get_full_help};
 
 #[derive(Clone)]
 pub struct Date;

crates/nu-command/src/date/humanize.rs

@@ -1,9 +1,8 @@
 use crate::date::utils::parse_date_from_string;
 use chrono::{DateTime, FixedOffset, Local};
 use chrono_humanize::HumanTime;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
+use nu_engine::command_prelude::*;
+
 #[derive(Clone)]
 pub struct SubCommand;
 

crates/nu-command/src/date/list_timezone.rs

@@ -1,10 +1,5 @@
 use chrono_tz::TZ_VARIANTS;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature,
-    Type, Value,
-};
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;

crates/nu-command/src/date/now.rs

@@ -1,9 +1,6 @@
 use chrono::Local;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Type, Value,
-};
+use nu_engine::command_prelude::*;
+
 #[derive(Clone)]
 pub struct SubCommand;
 

crates/nu-command/src/date/to_record.rs

@@ -1,11 +1,6 @@
 use crate::date::utils::parse_date_from_string;
 use chrono::{DateTime, Datelike, FixedOffset, Local, Timelike};
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, ShellError::DatetimeParseError,
-    ShellError::PipelineEmpty, Signature, Span, Type, Value,
-};
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -43,7 +38,7 @@ impl Command for SubCommand {
         let head = call.head;
         // This doesn't match explicit nulls
         if matches!(input, PipelineData::Empty) {
-            return Err(PipelineEmpty { dst_span: head });
+            return Err(ShellError::PipelineEmpty { dst_span: head });
         }
         input.map(move |value| helper(value, head), engine_state.ctrlc.clone())
     }
@@ -117,7 +112,7 @@ fn helper(val: Value, head: Span) -> Value {
         }
         Value::Date { val, .. } => parse_date_into_table(val, head),
         _ => Value::error(
-            DatetimeParseError {
+            ShellError::DatetimeParseError {
                 msg: val.to_debug_string(),
                 span: head,
             },

crates/nu-command/src/date/to_table.rs

@@ -1,11 +1,6 @@
 use crate::date::utils::parse_date_from_string;
 use chrono::{DateTime, Datelike, FixedOffset, Local, Timelike};
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, ShellError::DatetimeParseError,
-    ShellError::PipelineEmpty, Signature, Span, Type, Value,
-};
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;
@@ -43,7 +38,7 @@ impl Command for SubCommand {
         let head = call.head;
         // This doesn't match explicit nulls
         if matches!(input, PipelineData::Empty) {
-            return Err(PipelineEmpty { dst_span: head });
+            return Err(ShellError::PipelineEmpty { dst_span: head });
         }
         input.map(move |value| helper(value, head), engine_state.ctrlc.clone())
     }
@@ -116,7 +111,7 @@ fn helper(val: Value, head: Span) -> Value {
         }
         Value::Date { val, .. } => parse_date_into_table(val, head),
         _ => Value::error(
-            DatetimeParseError {
+            ShellError::DatetimeParseError {
                 msg: val.to_debug_string(),
                 span: head,
             },

crates/nu-command/src/date/to_timezone.rs

@@ -1,14 +1,7 @@
 use super::parser::datetime_in_timezone;
 use crate::date::utils::parse_date_from_string;
-use chrono::{DateTime, Local, LocalResult};
-use nu_engine::CallExt;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
-};
-
-use chrono::{FixedOffset, TimeZone};
+use chrono::{DateTime, FixedOffset, Local, LocalResult, TimeZone};
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;