Display avatars without overlap on MR homepage

Proposal

1. Display avatars without the overlap for reviewers in the merge request homepage.
2. For the overflow, we should display the avatars in a popover
   1. Display all of the reviewers in the popover sorted by requested changes, approved, commented, other. This can help with getting a better overview of the reviewers status in one view similar to the "Reviewers" section in the merge request sidebar.
   2. Overflow begins when reviewers > 4

Background

With displaying the review outcome on the avatar of the user it was unclear which outcome was attached to which reviewer http://gitlab.com/gitlab-org/gitlab/-/issues/494440#proposal-move-review-outcome-to-the-left. Even with that change it was confusing to people #515912 (comment 2530491958).

What if the original problem with this display was the overlapping of the avatars to begin with?

Design

Above is current design / Below is the proposed changes