buffer_diff: Remove git2 dependency from `buffer_diff` (#56013)

Split out of https://github.com/zed-industries/zed/pull/53453

Release Notes:

- N/A or Added/Fixed/Improved ...

Co-authored-by: Kieran Freitag <kfreitag@kieran.ca>
b5b52ada0cLukas Wirth committed on 5/26/2026, 2:28:02 PM· committed by GitHubparentb1bfde9
4 files changedLine totals unavailable