Missing user popover for user avatars in several places across GitLab

Summary

We introduced popovers showing detailed user info as a part of gitlab-foss#49090 (closed) back in %11.6 (via gitlab-foss#50157 (closed)), since then, the feature has evolved to be available across several places within GitLab.

User Popover

The problem

There are still many places, as listed below, where user popovers do not show up, thus making the feature behaviour inconsistent.

This makes it more difficult to gather information about that user and determine whether they are a GitLab team member or a member of the community.

Places where user popover on hover is missing

Note: Be sure to put an MR link next to list item if an MR is addressing it.

• Assignees across MRs in the right sidebar.
  • As pointed out in #416174 (comment 1446913812), we won't be adding popovers to reviewers list for now. This topic is moved to #416992 (closed) with an MR implementing it in !125555 (merged).
• Participants list across Issues, MRs, and Epics in the right sidebar. - !124511 (merged)
• Discussion note avatar across Issues, MRs, Epics, and Work Items. - !124517 (merged)
• Approvers list within Merge Request widget. - !125090 (merged)
• Usernames and avatars within Todos list. - !135171 (merged)

Proposal

Every place where we show a user avatar or prettified username (eg; within rendered markdown), hovering on it should show user popover. Adding a popover support to any avatar link element is fairly easy, as it needs 2 things as follows;

• Data attributes containing id (numeric ID) and username: data-user-id & data-username
• CSS class js-user-link