Improve abuse_reports page UX

Overview

The abuse_reports page in GitLab has bad UX.

• It's difficult to distinguish between the reporting user and the spam user.
• You cannot block a user and stay on the same page (a redirect happens)
• Pagination is broken https://gitlab.com/gitlab-org/gitlab-ce/issues/28059
• No bulk functions (bulk block users)
• To view user information you need to navigate away from the page (Show more information about a user on the abuse_reports, IP/project count etc)
• The reported user links to the profile page not to the admin/user page
• The button naming is wrong "Remove and report user" (user is already reported)

//cc @stanhu @awhildy @jschatz1 @briann