Remove dependency on resizable activity to enter PiP.

- Removing the requirement for activities to have both the
  resizeableActivity and supportsPictureInPicture attribute
  to enter PiP.  The activity may still be resized when
  entering picture-in-picture.

Bug: 34256643
Test: android.server.cts.ActivityManagerPinnedStackTests
Change-Id: If6bd4721c53072e5518f554a8c7598705517c132
18 files changed