Also check PiP activity visibility to determine if enter-pip

Originally assumed that we could detect "commit to transient-launch"
by the transient-launch task being visible at transition end; however,
because we can't defer activity launches, if an activity launches
after recents finishes, but before its finishTransition runs, the
launcher may actually be visREquested=false and we'd then skip
entering pip.

Resolve this by also checking if the pip app became invisible during
the transient-launch. This way, if either is true, we'll enter pip.

Bug: 286729035
Test: swipe maps navigation to pip and, before anim finishes, launch
      an app.
Change-Id: Ib4a1a199093f3266148ace0443eb800f69606cef