Properly expand lines in Rapid Diffs

Stanislav Lashmanovrequested to merge
slashmanov/rapid-diffs-line-expansion into master

What does this MR do and why?

Implements Implement line expansion (#498893 - closed).

Screenshots or screen recordings

Before After
Screen_Recording_2025-02-13_at_22.26.41 Screen_Recording_2025-02-13_at_22.23.25

How to set up and validate locally

  1. Enable rapid_diffs feature flag
  2. Open any merge request with changes
  3. Open Changes tab
  4. Add ?rapid_diffs=true to the URL, follow it
  5. Try expanding lines on any of the files

Merge request reports