git: Branch diff (#40188)

Release Notes:

- git: Adds the ability to view the diff of the current branch since
main

---------

Co-authored-by: Cole Miller <cole@zed.dev>
f45a9b351dConrad Irwin committed on 10/24/2025, 4:38:40 AM· committed by GitHubparentf11a3dc
18 files changedLine totals unavailable