Synchronize the app launch and taskbar stash animations.

Introduce FLAG_IGNORE_IN_APP to prevent taskbar from stashing
prematurely due to HomeTransitionListener signal.

Fixes leak by adding event callback to clear runnable when launcher is
destroyed.

Bug: 319162553
Test: Launch an app, note the two animations are synced
      Verified by locally introducing a startDelay (since otherwise it is hard to tell)
Flag: com.android.launcher3.sync_app_launch_with_taskbar_stash
Change-Id: I684c714bb84fb1717b0e26620f2aa938671eb19a