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/strings/format/date.rs

@@ -1,17 +1,10 @@
+use crate::{generate_strftime_list, parse_date_from_string};
 use chrono::{DateTime, Locale, TimeZone};
+use nu_engine::command_prelude::*;
 
-use nu_engine::CallExt;
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
-    Value,
-};
 use nu_utils::locale::{get_system_locale_string, LOCALE_OVERRIDE_ENV_VAR};
 use std::fmt::{Display, Write};
 
-use crate::{generate_strftime_list, parse_date_from_string};
-
 #[derive(Clone)]
 pub struct FormatDate;
 

crates/nu-command/src/strings/format/duration.rs

@@ -1,10 +1,5 @@
 use nu_cmd_base::input_handler::{operate, CmdArgument};
-use nu_engine::CallExt;
-use nu_protocol::ast::{Call, CellPath};
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
-};
+use nu_engine::command_prelude::*;
 
 struct Arguments {
     format_value: String,

crates/nu-command/src/strings/format/filesize.rs

@@ -1,11 +1,6 @@
 use nu_cmd_base::input_handler::{operate, CmdArgument};
-use nu_engine::CallExt;
-use nu_protocol::ast::{Call, CellPath};
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    format_filesize, Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape,
-    Type, Value,
-};
+use nu_engine::command_prelude::*;
+use nu_protocol::format_filesize;
 
 struct Arguments {
     format_value: String,

crates/nu-command/src/strings/format/format_.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 Format;