Quick actions for adding and removing epic relationships
internal customer since folks at GitLab (including me, VictorW) is already using quick actions to add/remove epic relationships to issues, and want to do this also for parent-child epic relationships.
- Quick action for adding and removing child epics, from within the parent epic.
- The addition/removal should appear in real-time in the UI, since this is already the case when you do it with the buttons/UI elements previously.