file_finder: Display single files already opened (#39911)

Closes https://github.com/zed-industries/zed/issues/24670

(Follow up of https://github.com/zed-industries/zed/pull/36856) cc
@ConradIrwin Thanks for your help

Release Notes:

Fixed: Keep non project files when filtering in File finder

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Signed-off-by: Benjamin <5719034+bnjjj@users.noreply.github.com>
Co-authored-by: Kirill Bulatov <mail4score@gmail.com>
ce2259ce51Coenen Benjamin committed on 10/15/2025, 4:50:37 PM· committed by GitHubparent6f97d74
3 files changedLine totals unavailable