Add HomeTransitionListener to launcher.

Fixes: 279514548
Bug: 284474103
Bug: 306053414

Flag: LEGACY ENABLE_HOME_TRANSITION_LISTENER DISABLED
Test: App launch -> Hotseat -> Taskbar stashes
      Transluscent app launch and launcher still visible -> No change
      Going home -> Hotseat visible

Change-Id: I6db5253ada3e3b37dfae124f3ee88a9805804fb8