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-engine/src/eval.rs

@@ -1,18 +1,17 @@
-use std::{borrow::Cow, fs::OpenOptions, path::PathBuf};
-
 use crate::{current_dir, current_dir_str, get_config, get_full_help};
 use nu_path::expand_path_with;
-use nu_protocol::debugger::DebugContext;
 use nu_protocol::{
     ast::{
         Assignment, Block, Call, Expr, Expression, ExternalArgument, PathMember, PipelineElement,
         PipelineRedirection, RedirectionSource, RedirectionTarget,
     },
+    debugger::DebugContext,
     engine::{Closure, EngineState, Redirection, Stack},
     eval_base::Eval,
     Config, FromValue, IntoPipelineData, IoStream, PipelineData, ShellError, Span, Spanned, Type,
     Value, VarId, ENV_VARIABLE_ID,
 };
+use std::{borrow::Cow, fs::OpenOptions, path::PathBuf};
 
 pub fn eval_call<D: DebugContext>(
     engine_state: &EngineState,