Fix a couple quickscrub issues

- Always launch workspace card if it's focused when quick scrub ends
  - Previously it would get stuck if quick scrub end was called on
    a background thread (since it was trying to touch RecentsView)
  - Prevent user from being able to get to the workspace card if
    starting quick scrub from an app by introducing bounds checking
- Prevent getting stuck in overview when ending quick scrub
  - There was a race condition where the task wouldn't launch if
    the animation to recents hadn't yet finished. Now there is a
    callback to ensure that launchTask() is always called after.

Bug: 70180755
Change-Id: I3c131011634880a97de8c2935c3ebdab26494b48