Can't leave a comment or draft comment on moved files with no changes

Summary

We recently shipped the ability to expand the content of a moved file with no changes.

However, leaving a comment or draft comment is failing.

Steps to reproduce

1. Open an MR with a renamed file, with no changes
2. Expand the content of that file in the Diff
3. Try to leave a comment
4. Try to leave a batch comment

Example Project

• gitlab-com/www-gitlab-com!58559 (diffs)
• andr3/meet.andr3.net!24 (diffs)

Proposal

On moved files that do not have any changes we should disable the comment button, with a tooltip saying:

Commenting on moved files is currently not supported

This will immediately relieve any concerns about errors or lost comments. Future feature enhancements to enable commenting are in #371752 (closed)