project_panel: Add notifications for drag-and-drop rename conflicts (#51138)

Follow-up https://github.com/zed-industries/zed/pull/51090

Adds workspace error notifications for project panel drag-and-drop moves
that fail on rename conflicts.

Release Notes:

- N/A
cb8088049eSmit Barmase committed on 3/9/2026, 11:27:00 PM· committed by GitHubparent7a4aaff
2 files changedLine totals unavailable