As a Watchlist Expiry user, I want to see a half star when I watch a page temporarily, so that I can easily & visually distinguish between permanently and temporarily watched pages.
**Background:** This is specifically the work to add the half star functionality. We are adding the popup to watch pages temporarily in T248496.
**Resources:**
* [[ https://meta.wikimedia.org/wiki/Community_Tech/Watchlist_Expiry | Watchlist Expiry project page ]]
* [[ https://wikimedia.invisionapp.com/public/share/8QYG7BMTJ#/screens/475685049 | Interactive mockup: Watch a page temporarily (via star) ]]
* [[ https://wikimedia.invisionapp.com/public/share/U5YGJG1RZ#/screens/475686737 | Interactive mockup: Unwatch a page (via star) ]]
**Acceptance Criteria:**
Show the half-star for pages that are watchlisted temporarily
Add the half-star animation when unwatching temporarily-watched pages