Cannot add comment to new images in merge request

Problem to solve

Comments can be added to images that were changed in an MR, but not images that are added/new

Further details

1. Commit a new image on a branch
2. Open an MR
3. Try to add a comment on it from the changes view
4. There is no way to accomplish step 3

Proposal

Add the same UI for commenting on images that is shown on changed images to new images

What does success look like, and how can we measure that?

Users will be able to add comments to new images committed in an MR