Multiple assignees update issue card design

Preface

1. EE now has an updated issue board card design
2. Multiple assignees for issues needs an updated issue board card design for displaying multiple assignees
3. We are going to refrain from rebasing the multiple_assignees_review branch until the very end

What does this MR do?

This is a backport of master's issue board card design change into the multiple_assignees_review branch to make it easier to make changes on the new design before the review branch is rebased against master.

Are there points in the code the reviewer needs to double check?

Shouldn't be