Deals with https://github.com/zed-industries/community/issues/2347
Part of https://github.com/zed-industries/community/issues/1538

Now file finder will match all gitignored worktree entries.
Zed does not traverse gitignored dirs by default, which means that not
all gitignored files will be matches, but all that were toggled in
project panel and all root non-directory gitignored entries will be now
used, hopefully causing less questions.

Release Notes:

- Improved file finder to match all gitignored files that were added
into worktrees (e.g. due to opening gitignored directories in project
panel)