WIP: 36220 Adds file diff for each commit in a file's commit history page.

What does this MR do?

This adds a file-diff view for each commit in a file's commit history.

Why was this MR needed?

To close/fulfill #36220 (moved)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #36220 (moved)