Synchronize the app launch and taskbar stash animations.

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

Bug: 345768019
Fixes: 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.enable_scaling_reveal_home_animation
Change-Id: Ibb64e0321f33cf81e337fc7c1b2c3edfb23e6ba4