git: Enable git stash in git panel (#32821)

Related discussion #31484

Release Notes:

- Added a menu entry on the git panel to git stash and git pop stash. 

Preview: 


![Screenshot-2025-06-17_08:26:36](https://github.com/user-attachments/assets/d3699ba4-511f-4c7b-a7cc-00a295d01f64)

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Co-authored-by: Cole Miller <cole@zed.dev>
07252c3309Alvaro Parker committed on 7/25/2025, 11:15:54 PM· committed by GitHubparent4d00d07
10 files changedLine totals unavailable