settings: Load `.zed/settings.json` even if .gitignored (#13370)

This fixes #4432 by ensuring that we scan & watch the `.zed` folder,
just like we watch the `.git`, for changes.

Release Notes:

- Settings are now loaded from local `.zed/settings.json` files even if
they are `.gitignore`d.
([#4432](https://github.com/zed-industries/zed/issues/4432)).

Co-authored-by: Bennet <bennet@zed.dev>