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/math/abs.rs

@@ -1,6 +1,4 @@
-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/math/avg.rs

@@ -1,10 +1,8 @@
-use crate::math::reducers::{reducer_for, Reduce};
-use crate::math::utils::run_with_function;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
+use crate::math::{
+    reducers::{reducer_for, Reduce},
+    utils::run_with_function,
 };
+use nu_engine::command_prelude::*;
 
 const NS_PER_SEC: i64 = 1_000_000_000;
 #[derive(Clone)]

crates/nu-command/src/math/ceil.rs

@@ -1,6 +1,4 @@
-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/math/floor.rs

@@ -1,6 +1,4 @@
-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/math/log.rs

@@ -1,9 +1,4 @@
-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 nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;

crates/nu-command/src/math/math_.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 MathCommand;

crates/nu-command/src/math/max.rs

@@ -1,10 +1,8 @@
-use crate::math::reducers::{reducer_for, Reduce};
-use crate::math::utils::run_with_function;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
+use crate::math::{
+    reducers::{reducer_for, Reduce},
+    utils::run_with_function,
 };
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;

crates/nu-command/src/math/median.rs

@@ -1,13 +1,7 @@
+use crate::math::{avg::average, utils::run_with_function};
+use nu_engine::command_prelude::*;
 use std::cmp::Ordering;
 
-use crate::math::avg::average;
-use crate::math::utils::run_with_function;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
-};
-
 #[derive(Clone)]
 pub struct SubCommand;
 

crates/nu-command/src/math/min.rs

@@ -1,10 +1,8 @@
-use crate::math::reducers::{reducer_for, Reduce};
-use crate::math::utils::run_with_function;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
+use crate::math::{
+    reducers::{reducer_for, Reduce},
+    utils::run_with_function,
 };
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;

crates/nu-command/src/math/mode.rs

@@ -1,11 +1,6 @@
 use crate::math::utils::run_with_function;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
-};
-use std::cmp::Ordering;
-use std::collections::HashMap;
+use nu_engine::command_prelude::*;
+use std::{cmp::Ordering, collections::HashMap};
 
 #[derive(Clone)]
 pub struct SubCommand;

crates/nu-command/src/math/product.rs

@@ -1,10 +1,8 @@
-use crate::math::reducers::{reducer_for, Reduce};
-use crate::math::utils::run_with_function;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
+use crate::math::{
+    reducers::{reducer_for, Reduce},
+    utils::run_with_function,
 };
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;

crates/nu-command/src/math/round.rs

@@ -1,9 +1,4 @@
-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, SyntaxShape, Type, Value,
-};
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;

crates/nu-command/src/math/sqrt.rs

@@ -1,6 +1,4 @@
-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/math/stddev.rs

@@ -1,11 +1,6 @@
 use super::variance::compute_variance as variance;
 use crate::math::utils::run_with_function;
-use nu_engine::CallExt;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
-};
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;

crates/nu-command/src/math/sum.rs

@@ -1,10 +1,8 @@
-use crate::math::reducers::{reducer_for, Reduce};
-use crate::math::utils::run_with_function;
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    record, Category, Example, PipelineData, ShellError, Signature, Span, Type, Value,
+use crate::math::{
+    reducers::{reducer_for, Reduce},
+    utils::run_with_function,
 };
+use nu_engine::command_prelude::*;
 
 #[derive(Clone)]
 pub struct SubCommand;

crates/nu-command/src/math/utils.rs

@@ -1,8 +1,6 @@
 use core::slice;
-
-use indexmap::map::IndexMap;
-use nu_protocol::ast::Call;
-use nu_protocol::{IntoPipelineData, PipelineData, ShellError, Span, Value};
+use indexmap::IndexMap;
+use nu_protocol::{ast::Call, IntoPipelineData, PipelineData, ShellError, Span, Value};
 
 pub fn run_with_function(
     call: &Call,

crates/nu-command/src/math/variance.rs

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