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/system/complete.rs

@@ -1,10 +1,5 @@
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, IntoPipelineData, IntoSpanned, IoStream, PipelineData, Record, ShellError,
-    Signature, Type, Value,
-};
-
+use nu_engine::command_prelude::*;
+use nu_protocol::IoStream;
 use std::thread;
 
 #[derive(Clone)]

crates/nu-command/src/system/exec.rs

@@ -1,10 +1,6 @@
 use super::run_external::create_external_command;
-use nu_engine::current_dir;
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, IoStream, PipelineData, ShellError, Signature, Span, SyntaxShape, Type,
-};
+use nu_engine::{command_prelude::*, current_dir};
+use nu_protocol::IoStream;
 
 #[derive(Clone)]
 pub struct Exec;

crates/nu-command/src/system/nu_check.rs

@@ -1,11 +1,6 @@
-use nu_engine::{env::get_config, find_in_dirs_env, get_dirs_var_from_call, CallExt};
+use nu_engine::{command_prelude::*, env::get_config, find_in_dirs_env, get_dirs_var_from_call};
 use nu_parser::{parse, parse_module_block, parse_module_file_or_dir, unescape_unquote_string};
-use nu_protocol::ast::Call;
-use nu_protocol::engine::{Command, EngineState, Stack, StateWorkingSet};
-use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
-};
-
+use nu_protocol::engine::StateWorkingSet;
 use std::path::Path;
 
 #[derive(Clone)]

crates/nu-command/src/system/ps.rs

@@ -1,19 +1,7 @@
 #[cfg(windows)]
 use itertools::Itertools;
-use nu_engine::CallExt;
-#[cfg(all(
-    unix,
-    not(target_os = "macos"),
-    not(target_os = "windows"),
-    not(target_os = "android"),
-))]
-use nu_protocol::Span;
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, IntoInterruptiblePipelineData, PipelineData, Record, ShellError, Signature,
-    Type, Value,
-};
+use nu_engine::command_prelude::*;
+
 #[cfg(all(
     unix,
     not(target_os = "freebsd"),
@@ -22,7 +10,6 @@ use nu_protocol::{
     not(target_os = "android"),
 ))]
 use procfs::WithCurrentSystemInfo;
-
 use std::time::Duration;
 
 #[derive(Clone)]

crates/nu-command/src/system/registry_query.rs

@@ -1,10 +1,5 @@
-use nu_engine::CallExt;
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
-};
+use nu_engine::command_prelude::*;
+
 use windows::{core::PCWSTR, Win32::System::Environment::ExpandEnvironmentStringsW};
 use winreg::{enums::*, types::FromRegValue, RegKey};
 

crates/nu-command/src/system/run_external.rs

@@ -1,25 +1,18 @@
 use nu_cmd_base::hook::eval_hook;
-use nu_engine::env_to_strings;
-use nu_engine::get_eval_expression;
-use nu_engine::CallExt;
-use nu_protocol::{
-    ast::{Call, Expr},
-    did_you_mean,
-    engine::{Command, EngineState, Stack},
-    Category, Example, IntoSpanned, IoStream, ListStream, NuGlob, PipelineData, RawStream,
-    ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
-};
+use nu_engine::{command_prelude::*, env_to_strings, get_eval_expression};
+use nu_protocol::{ast::Expr, did_you_mean, IoStream, ListStream, NuGlob, RawStream};
 use nu_system::ForegroundChild;
 use nu_utils::IgnoreCaseExt;
 use os_pipe::PipeReader;
 use pathdiff::diff_paths;
-use std::collections::HashMap;
-use std::io::{BufRead, BufReader, Read, Write};
-use std::path::{Path, PathBuf};
-use std::process::{Command as CommandSys, Stdio};
-use std::sync::mpsc;
-use std::sync::Arc;
-use std::thread;
+use std::{
+    collections::HashMap,
+    io::{BufRead, BufReader, Read, Write},
+    path::{Path, PathBuf},
+    process::{Command as CommandSys, Stdio},
+    sync::{mpsc, Arc},
+    thread,
+};
 
 #[derive(Clone)]
 pub struct External;

crates/nu-command/src/system/sys.rs

@@ -1,11 +1,6 @@
-use chrono::prelude::DateTime;
-use chrono::Local;
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    record, Category, Example, IntoPipelineData, LazyRecord, PipelineData, Record, ShellError,
-    Signature, Span, Type, Value,
-};
+use chrono::{DateTime, Local};
+use nu_engine::command_prelude::*;
+use nu_protocol::LazyRecord;
 use std::time::{Duration, UNIX_EPOCH};
 use sysinfo::{
     Components, CpuRefreshKind, Disks, Networks, System, Users, MINIMUM_CPU_UPDATE_INTERVAL,

crates/nu-command/src/system/which_.rs

@@ -1,16 +1,6 @@
 use log::trace;
-use nu_engine::env;
-use nu_engine::CallExt;
-use nu_protocol::record;
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
-    Spanned, SyntaxShape, Type, Value,
-};
-
-use std::ffi::OsStr;
-use std::path::Path;
+use nu_engine::{command_prelude::*, env};
+use std::{ffi::OsStr, path::Path};
 
 #[derive(Clone)]
 pub struct Which;