Get PictureInPictureParams from top activity

Task#getPictureInPictureParams used to get the params from root activity
and it is okay doing so without autoEnterPip since the activity to be
pinned will be put in a task with one and only one activity.

With autoEnterPip, it it possible that the root activity has no
PictureInPictureParams being attached when the transition starts in
Launcher side, switch to use the PictureInPictureParams tied to the top
visible activity here.

Fixes also
- when this happens, we need to reset the window crop leash on the
  original task in FullscreenTaskListener#onTaskInfoChanged
- ensure the reparented task inherits the current bounds
- ensure we do not hide the leash in Task#setHasBeenVisible by setting
  mHasBeenVisible=true on the newly created task

Video: http://rcll/aaaaaabFQoRHlzixHdtY/gIO4G5dybW7tJWXihkhXfE
Bug: 177335910
Test: see video
Change-Id: I198443b93b7d8cc11108f0d0606f98eac58c07b7