refactor(directory): Introduce `logical-path` argument which allows a shell to explicitly specify both a logical and physical filesystem path (#2104)

* refactor(directory): Introduce `logical-path` argument which allows a shell to explicitly specify both a logical and physical filesystem path

Fix `directory::module` to consume both path and logical-path (if provided).  The "logical" path is preferred when rendering the "display path", while the "physical" path is used to resolve the "read only" flag. Repo- and home-directory contraction behavior is maintained, based on the logical path if it is set, or the physical path if it is not.

The custom "get_current_dir" logic has been removed entirely, and the `directory` module now relies on `context.current_dir` / `context.logical_dir` entirely.

Changes have been made to `init/starship.ps1` to work with this new flag:
- Calculate and pass "physical" and "logical" paths explicitly (as other shells do not pass `--logical-path` that they fall back to rendering the physical path)
- Moved the "powershell provider prefix" cleanup code to the PowerShell script - this code _should_ now support any kind of powershell path prefix.

* fix(powershell): Fix an issue with trailing backslashes on file paths causing command line parsing issues.

This is a bit of a footgun!
The work-around chosen is to append a trailing space when a path string ends with a backslash, and then trim any extra whitespace away in the Context constructor.
Other alternatives considered and rejected:
1. Always trim trailing backslashes as the filesystem generally doesn't need them.
2. Escape trailing backslashes with another backslash. This proved complex as PS only quotes string args when the string includes some whitespace, and other backslashes within the string apparently don't need to be escaped.

* fix(powershell): Use Invoke-Native pattern for safely invoking native executables with strings which may contain characters which need to be escaped carefully.

* fix(context): Remove superfluous argument trims

These were in place to clean up extra whitespace sometimes injected by starship.ps1::prompt, and are no longer required with the new Invoke-Native helper in place.

* refactor(directory): Clean up the semantics of `logical_dir` defaulting it to `current_dir` but overridable by the `--logical-dir` flag.

- Restore `use_logical_path` config flag.
- Always attempt to contract repo paths from the `current_dir`.

* fix(directory) :Use logical_dir for contracting the home directory

This keeps the two calls to contract_path in sync.

* fix(directory): Remove test script

* refactor(directory): Convert current_dir to canonical filesystem path when use_logical_path = false

- This requires some clean-up to remove the extended-path prefix on Windows
- The configured logical_dir is ignored entirely in this mode - we calculate a new logical_dir by cleaning up the physical_dir path for display.
- Test coverage

* fix(directory): Use AsRef style for passing Path arguments

* fix(directory): Strip the windows extended-path prefix from the display string later in the render process

* fix(docs): Update docs/config/README.md for use_logical_path

* refactor(context): Populate `current_dir` from `--path` or `std::env::current_dir`, populate `logical_dir` from `--logical-path` or the `PWD` env var

- `current_dir` is always canonicalized
- On Windows, `current_dir` will have an extended-path prefix
- `logical_dir` is now always set
- `directory::module` now just selects between `current_dir` and `logical_dir` when picking which path to render
- Test coverage

* fix(directory): Fix path comparison operations in directory to ignore differences between path prefixes

- Added PathExt extension trait which adds `normalised_equals`, `normalised_starts_with` and `without_prefix`

* fix(path): Add test coverage for PathExt on *nix

* fix(directory): Test coverage for `contract_repo_path`, `contract_path` with variations of verbatim and non-verbatim paths

* fix(directory): Update path-slash to latest

This fixes the issue with the trailing character of some Windows paths being truncated, e.g. `\\server\share` and `C:`

* fix(powershell): Improve UTF8 output handling, argument encoding

- Use `ProcessStartInfo` to launch native executable, replacing manual UTF8 output encoding handling
- If we detect we're on PWSH6+ use the new `System.Diagnostics.ProcessStartInfo.ArgumentList` parameter, otherwise manually escape the argument string
- Move `Get-Cwd` and `Invoke-Native` into the prompt function scope so that they don't leak into the user's shell scope

* fix(path): Make PathExt methods no-ops on *nix

* fix(path): Cargo fmt

* fix(powershell): Remove typo ';'. Fix variable assignment lint.

1 files changed, 5 insertions, 5 deletions

diff --git a/docs/config/README.md b/docs/config/README.md
index 5b77c304b..32428b784 100644
--- a/docs/config/README.md
+++ b/docs/config/README.md
@@ -666,11 +666,11 @@ it would have been `nixpkgs/pkgs`.
 <details>
 <summary>This module has a few advanced configuration options that control how the directory is displayed.</summary>
 
-| Advanced Option             | Default | Description                                                                              |
-| --------------------------- | ------- | ---------------------------------------------------------------------------------------- |
-| `substitutions`             |         | A table of substitutions to be made to the path.                                         |
-| `fish_style_pwd_dir_length` | `0`     | The number of characters to use when applying fish shell pwd path logic.                 |
-| `use_logical_path`          | `true`  | Displays the logical path provided by the shell (`PWD`) instead of the path from the OS. |
+| Advanced Option             | Default | Description                                                               |
+| --------------------------- | ------- | ------------------------------------------------------------------------- |
+| `substitutions`             |         | A table of substitutions to be made to the path.                          |
+| `fish_style_pwd_dir_length` | `0`     | The number of characters to use when applying fish shell pwd path logic.  |
+| `use_logical_path`          | `true`  | If `true` render the logical path sourced from the shell via `PWD` or `--logical-path`. If `false` instead render the physical filesystem path with symlinks resolved. |
 
 `substitutions` allows you to define arbitrary replacements for literal strings that occur in the path, for example long network
 prefixes or development directories (i.e. Java). Note that this will disable the fish style PWD.