project panel: Allow selecting multiple entries & add support for multiselect actions (#12363)

Fixes #4983 
TODO:
- [x] Improve release note.
- [x] Tests

Release Notes:

- Project panel now supports selecting multiple entries via cmd-click
and shift-click/shift-up/shift-down.
- Added support for handling multiple selected project panel entries to
Cut, Copy, Trash and Delete actions.
016a1444a7Piotr Osiewicz committed on 5/28/2024, 1:51:23 PM· committed by GitHubparent1cf3496
3 files changedLine totals unavailable