Refactor Watchlist code so mobile can be more consistent

There are various bugs around the mobile watchlist that are caused by
mobile reimplementing the watchlist due to the core code's inflexibility

This slight change makes it possible for the A-Z mode on mobile to use the
same code as desktop
See: 56817

Change-Id: Id04c8b1f41894c724ca8ea403078b3389666ebc9
Merge "Refactor Watchlist code so mobile can be more consistent"