Fix entering PiP transition in button navigation mode

Included in this CL
- when there is no source rect hint, use a content overlay during the transition
- otherwise, take account the display cutout to offset/inset the source
  rect hint

Test with following variants when entering PiP in button nav
- from 0 / 90 / 270 rotation
- with or without source rect hint
- display cutout mode set to default or shortEdge

Video: http://recall/-/aaaaaabFQoRHlzixHdtY/cxk4vy8VenQPSv83vHEs22
Bug: 191310680
Test: manual, see the test cases listed and video above
Change-Id: Ie54a54de6e55397e25024373ea4e2855fde2d9f7