git: Don't show binary files in past commit view (#46312)

Also improves the commit view to use the same status-based buffer header
visual overrides as the project diff as a driveby.

Fixes https://github.com/zed-industries/zed/issues/45735

Release Notes:

- git: Binary files are no longer shown in garbled form when viewing an
old commit.
3835d40035Cole Miller committed on 1/8/2026, 3:07:41 AM· committed by GitHubparent74c3608
8 files changedLine totals unavailable