Feature: PWD-per-drive to facilitate working on multiple drives at Windows (#14411)

This PR implements PWD-per-drive as described in discussion #14355

# Description
On Windows, CMD or PowerShell assigns each drive its own current
directory. For example, if you are in 'C:\Windows', switch to 'D:', and
navigate to 'D:\Game', you can return to 'C:\Windows' by simply typing
'C:'.

This PR enables Nushell on Windows to have the same capability, allowing
each drive to maintain its own PWD (Present Working Directory).

# User-Facing Changes
Currently, 'cd' or 'ls' only accept absolute paths if the path starts
with 'C:' or another drive letter. With PWD-per-drive, users can use
'cd' (or auto cd) and 'ls' in the same way as 'cd' and 'dir' in
PowerShell, or similarly to 'cd' and 'dir' in CMD (noting that cd in CMD
has slightly different behavior, 'cd' for another drive only changes
current directory of that drive, but does not switch there).

Interaction example on switching between drives:
```Nushell
~>D:
D:\>cd Test
D:\Test\>C:
~>D:
D:\Test\>C:
~>cd D:..
D:\>C:x/../y/../z/..
~>cd D:Test\Test
D:\Test\Test>C:
~>D:...
D:\>
```
Interaction example on auto-completion at cmd line:
```Nushell
~>cd D:\test[Enter]
D:\test>~[Enter]
~>D:[TAB]
~>D:\test[Enter]
D:\test>c:.c[TAB]
c:\users\nushell\.cargo\ c:\users\nushell\.config\
```
Interaction example on pass PWD-per-drive to child process: (Note CMD
will use it, but PowerShell will ignore it though it still prepares such
info for child process)
```Nushell
~>cd D:\Test
D:\Test>cd E:\Test
E:\Test\>~
~>CMD
Microsoft Windows [Version 10.0.22631.4460]
(c) Microsoft Corporation. All rights reserved.

C:\Users\Nushell>d:
D:\Test>e:
E:\Test>
```

# Brief Change Description
 
1.Added 'crates/nu-path/src/pwd_per_drive.rs' to implement a 26-slot
array mapping drive letters to PWDs. Test cases are included in the same
file, along with a doctest for the usage of PWD-per-drive.
2. Modified 'crates/nu-path/src/lib.rs' to declare module of
pwd_per_drive and export struct for PWD-per-drive.
3. Modified 'crates/nu-protocol/src/engine/stack.rs' to sync PWD when
set_cwd() is called. Add PWD-per-drive map as member. Clone between
parent and child. Stub/proxy for nu_path::expand_path_with() to
facilitate filesystem commands using PWD-per-drive.
4. Modified 'crates/nu-cli/src/repl.rs' auto_cd uses PWD-per-drive to
expand path.
5. Modified 'crates/nu-cli/src/completions/completion_common.rs' to
expand relative path when press [TAB] at command line.
6. Modified 'crates/nu-engine/src/env.rs' to collect PWD-per-drive info
as env vars for child process as CMD or PowerShell do, this can let
child process inherit PWD-per-drive info.
7. Modified 'crates/nu-engine/src/eval.rs', caller clone callee's
PWD-per-drive info, supporting 'def --env'
8. Modified 'crates/nu-engine/src/eval_ir.rs', 'def --env' support.
Remove duplicated fn redirect_env()
9. Modified 'src/run.rs', to init PWD-per-drive when startup.

filesystem commands that modified:
1. Modified 'crates/nu-command/src/filesystem/cd.rs', 1 line change to
use stackscoped PWD-per-drive.
Other commands, commit pending....

Local test def --env OK:
```nushell
E:\study\nushell> def --env env_cd_demo [] {                 
:::     cd ~
:::     cd D:\Project
:::     cd E:Crates
::: }
E:\study\nushell>                                                   
E:\study\nushell> def cd_no_demo [] {                   
:::     cd ~
:::     cd D:\Project
:::     cd E:Crates
::: }
E:\study\nushell> cd_no_demo                                 
E:\study\nushell> C:
C:\>D:
D:\>E:                                     
E:\study\nushell>env_cd_demo
E:\study\nushell\crates> C:
~>D:
D:\Project>E:                                     
E:\study\nushell\crates>     
```

# Tests + Formatting

- `cargo fmt --all -- --check` passed.
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used`
passed.
- `cargo test --workspace` passed on Windows developer mode and Ubuntu.
- `cargo run -- -c "use toolkit.nu; toolkit test stdlib"` passed.
- nushell:
```
> use toolkit.nu  # or use an `env_change` hook to activate it automatically
> toolkit check pr
> ```
passed

---------

Co-authored-by: pegasus.cadence@gmail.com <pegasus.cadence@gmail.com>

crates/nu-engine/src/eval_ir.rs

@@ -1,6 +1,6 @@
 use std::{borrow::Cow, fs::File, sync::Arc};
 
-use nu_path::{expand_path_with, AbsolutePathBuf};
+use nu_path::AbsolutePathBuf;
 use nu_protocol::{
     ast::{Bits, Block, Boolean, CellPath, Comparison, Math, Operator},
     debugger::DebugContext,
@@ -14,7 +14,7 @@ use nu_protocol::{
 };
 use nu_utils::IgnoreCaseExt;
 
-use crate::{eval::is_automatic_env_var, eval_block_with_early_return};
+use crate::{eval::is_automatic_env_var, eval_block_with_early_return, redirect_env};
 
 /// Evaluate the compiled representation of a [`Block`].
 pub fn eval_ir_block<D: DebugContext>(
@@ -870,7 +870,7 @@ fn literal_value(
                 Value::string(path, span)
             } else {
                 let cwd = ctx.engine_state.cwd(Some(ctx.stack))?;
-                let path = expand_path_with(path, cwd, true);
+                let path = ctx.stack.expand_path_with(path, cwd, true);
 
                 Value::string(path.to_string_lossy(), span)
             }
@@ -890,7 +890,7 @@ fn literal_value(
                     .cwd(Some(ctx.stack))
                     .map(AbsolutePathBuf::into_std_path_buf)
                     .unwrap_or_default();
-                let path = expand_path_with(path, cwd, true);
+                let path = ctx.stack.expand_path_with(path, cwd, true);
 
                 Value::string(path.to_string_lossy(), span)
             }
@@ -1405,7 +1405,8 @@ enum RedirectionStream {
 /// Open a file for redirection
 fn open_file(ctx: &EvalContext<'_>, path: &Value, append: bool) -> Result<Arc<File>, ShellError> {
     let path_expanded =
-        expand_path_with(path.as_str()?, ctx.engine_state.cwd(Some(ctx.stack))?, true);
+        ctx.stack
+            .expand_path_with(path.as_str()?, ctx.engine_state.cwd(Some(ctx.stack))?, true);
     let mut options = File::options();
     if append {
         options.append(true);
@@ -1485,26 +1486,3 @@ fn eval_iterate(
         eval_iterate(ctx, dst, stream, end_index)
     }
 }
-
-/// Redirect environment from the callee stack to the caller stack
-fn redirect_env(engine_state: &EngineState, caller_stack: &mut Stack, callee_stack: &Stack) {
-    // TODO: make this more efficient
-    // Grab all environment variables from the callee
-    let caller_env_vars = caller_stack.get_env_var_names(engine_state);
-
-    // remove env vars that are present in the caller but not in the callee
-    // (the callee hid them)
-    for var in caller_env_vars.iter() {
-        if !callee_stack.has_env_var(engine_state, var) {
-            caller_stack.remove_env_var(engine_state, var);
-        }
-    }
-
-    // add new env vars from callee to caller
-    for (var, value) in callee_stack.get_stack_env_vars() {
-        caller_stack.add_env_var(var, value);
-    }
-
-    // set config to callee config, to capture any updates to that
-    caller_stack.config.clone_from(&callee_stack.config);
-}