Improve PIP enter transition w/ gesture nav (3/N)

Directly transition Activity to PiP mode in launcher if the Activity
claims auto-pip support. Video is taken by commenting out the
requirement of setting the auto-pip flag.

Note that we need app to actively push up-to-dated
PictureInPictureParams to the framework, otherwise we won't be get
- PictureInPictureParams on first entering
- Staled PictureInPictureParams if the aspect ratio is changed

Video: http://rcll/aaaaaabFQoRHlzixHdtY/abenIxLFI1pZzF2O8t4TbS
Bug: 143965596
Test: see demo videos
Change-Id: Iea9a6ff39a79431ac1afa14aea812c500b3ca3b2