Add windowing layer into TransitionRequestInfo

Used to propagate the request to Shell.
Includes the layer and callback to report the result back.

Bug: 399376001
Bug: 443206707
Test: n/a
Flag: com.android.window.flags.enable_interactive_picture_in_picture
Change-Id: I571ea6e794be1d3b2c105ea22b5b029c54706af7