Reviewer Roulette suggestions should include a tooltip

Problem to solve

The suggestions from RR are great but there's no immediate way to see the status / availability of a reviewer.

Suggestion

Add a tooltip to the suggested reviewer links which contains user information, as done for discussions.

Additional information

Reviewer information is defined here: https://gitlab.com/gitlab-org/gitlab-roulette/-/blob/master/lib/team_member.rb

A popover / tooltip can be rendered via https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/assets/javascripts/user_popovers.js#L62