Backport of add-epic-sidebar
What does this MR do?
Backport of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3253
Are there points in the code the reviewer needs to double check?
Shouldn't be
Why was this MR needed?
Backport of some new shared components and CSS changes
Screenshots (if relevant)
None
Does this MR meet the acceptance criteria?
- Review
-
Has been reviewed by Frontend
-