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/env/config/config_.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 ConfigMeta;

crates/nu-command/src/env/config/config_env.rs

@@ -1,12 +1,6 @@
-use nu_engine::{env_to_strings, CallExt};
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Type, Value,
-};
-
 use super::utils::gen_command;
 use nu_cmd_base::util::get_editor;
+use nu_engine::{command_prelude::*, env_to_strings};
 
 #[derive(Clone)]
 pub struct ConfigEnv;

crates/nu-command/src/env/config/config_nu.rs

@@ -1,12 +1,6 @@
-use nu_engine::{env_to_strings, CallExt};
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Type, Value,
-};
-
 use super::utils::gen_command;
 use nu_cmd_base::util::get_editor;
+use nu_engine::{command_prelude::*, env_to_strings};
 
 #[derive(Clone)]
 pub struct ConfigNu;

crates/nu-command/src/env/config/config_reset.rs

@@ -1,10 +1,6 @@
 use chrono::Local;
-use nu_engine::CallExt;
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Type,
-};
+use nu_engine::command_prelude::*;
+
 use nu_utils::{get_default_config, get_default_env};
 use std::io::Write;
 

crates/nu-command/src/env/config/utils.rs

@@ -1,9 +1,6 @@
-use std::collections::HashMap;
-use std::path::PathBuf;
-
-use nu_protocol::{IoStream, Span, Spanned};
-
 use crate::ExternalCommand;
+use nu_protocol::{IoStream, Span, Spanned};
+use std::{collections::HashMap, path::PathBuf};
 
 pub(crate) fn gen_command(
     span: Span,

crates/nu-command/src/env/export_env.rs

@@ -1,10 +1,5 @@
-use nu_engine::{get_eval_block, redirect_env, CallExt};
-
-use nu_protocol::{
-    ast::Call,
-    engine::{Closure, Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
-};
+use nu_engine::{command_prelude::*, get_eval_block, redirect_env};
+use nu_protocol::engine::Closure;
 
 #[derive(Clone)]
 pub struct ExportEnv;

crates/nu-command/src/env/load_env.rs

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

crates/nu-command/src/env/source_env.rs

@@ -1,15 +1,8 @@
-use std::path::PathBuf;
-
 use nu_engine::{
-    find_in_dirs_env, get_dirs_var_from_call, get_eval_block_with_early_return, redirect_env,
-    CallExt,
-};
-use nu_protocol::ast::Call;
-
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Type, Value,
+    command_prelude::*, find_in_dirs_env, get_dirs_var_from_call, get_eval_block_with_early_return,
+    redirect_env,
 };
+use std::path::PathBuf;
 
 /// Source a file for environment variables.
 #[derive(Clone)]

crates/nu-command/src/env/with_env.rs

@@ -1,13 +1,7 @@
+use nu_engine::{command_prelude::*, eval_block};
+use nu_protocol::{debugger::WithoutDebug, engine::Closure};
 use std::collections::HashMap;
 
-use nu_engine::{eval_block, CallExt};
-use nu_protocol::debugger::WithoutDebug;
-use nu_protocol::{
-    ast::Call,
-    engine::{Closure, Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
-};
-
 #[derive(Clone)]
 pub struct WithEnv;