As a watchlist expiry user, I want the Pop-Up in StructuredDiscussions to be OOUI, so it remains consistent with the work done on T249259 and so that the users can access the feature via StructuredDiscussions.
Background: This is a task that stems from Dom's comment in the original Pop-Up OOUI ticket.
Acceptance Criteria:
- The user should be able to watch a page via the star & generate OOUI message in StructuredDiscussions
- The general behavior should follow the specifications of T249259