Enable manual worktree organization (#11504)

Release Notes:

- Preserve order of worktrees in project
([#10883](https://github.com/zed-industries/zed/issues/10883)).
- Enable drag-and-drop reordering for project worktrees

Note: worktree order is not synced during collaboration but guests can
reorder their own project panels.

![Reordering
worktrees](https://github.com/zed-industries/zed/assets/1347854/1c63d83c-5d4e-4b55-b840-bfbf32521b2a)

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Co-authored-by: Kirill Bulatov <kirill@zed.dev>