What does this MR do?
This improves the new/edit MR page to have the latest UX for the approver selection.
This was originally closing #1526 (closed), but I now see that is actually completely out of scope. Please ignore the branch name.
Now closes #2228.
Are there points in the code the reviewer needs to double check?
Why was this MR needed?
Screenshots (if relevant)
Does this MR meet the acceptance criteria?
Changelog entry added, if necessary
API support added
Added for this feature/bug
All builds are passing
Conform by the merge request performance guides
Conform by the style guides
Branch has no merge conflicts with
master(if it does - rebase it please)
Squashed related commits together
What are the relevant issue numbers?