Fix file_type matching for local single-file worktrees

[notpeter]

Objective

• Fixes: Single File Worktrees don't respect file_types globs #60304

Solution

Fixes custom file_types language matching for single-file worktrees.
Adds a new file_system_abs_path API with full local or remote filesystem paths for glob matching.

Testing

New tests ensure file_types takes precedence over path_suffixes in single file worktrees, both locally and remotely.

I manually validated builds with this change are also fixed. Validation:

1. Install ini extension
2. Add "file_types": {"Plain Text": ["**/.ssh/config"]} to your zed settings.json:
3. From a command prompt:

   mkdir -p /tmp/foo/.ssh/
   touch  /tmp/foo/.ssh/config
   # these work now:
   cargo run -- /tmp/foo/.ssh/config
   cargo run -- ssh://think21:~/.ssh/config

Self-Review Checklist:

• [Yes] I've reviewed my own diff for quality, security, and reliability
• [N/A] Unsafe blocks (if any) have justifying comments
• [N/A] The content adheres to Zed's UI standards (UX/UI and icon guidelines)
• [Yes] Tests cover the new/changed behavior
• [Yes] Performance impact has been considered and is acceptable

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Release Notes:

• Fixed language association for file_type path globs with single-file worktrees