Don't rely on intent to call back from activity tracker

- The intent is not updated in certain cases which means that the
  callback may not be made if Launcher gets recreated. Instead
  have the tracker manage the set of registered callbacks.
- This change allows AbsSwipeUpHandler to continue to receive
  onActivityInit calls even if Launcher restarts, and also to
  handle a case where restarting while waiting for a page-settling
  callback will continue to finish the gesture.

Bug: 183962705
Test: Force recreate at various points in the gesture

Change-Id: Ib5ead8c868e798e26e56776f57bd715c79d087cd