git: Make GitPanel more responsive to long-running staging ops (#41667)

Currently, this only applies to long-running individually selected
unstaged files in the git panel. Next up I would like to make this work
for `Stage All`/`Unstage All` however this will most likely require
pushing `PendingOperation` into `GitStore` (from the `GitPanel`).

Release Notes:

- N/A
aa61f25795Jakub Konka committed on 10/31/2025, 9:47:49 PM· committed by GitHubparentd406409
2 files changedLine totals unavailable