Move PiP window upon tabletop mode changes

System property persist.wm.debug.enable_move_floating_window_in_tabletop
can be used to toggle the feature.

Further, System property persist.wm.debug.prefer_top_half_in_tabletop
can be used to control which half is preferred. This preferred location
is used for moving the PiP and affects the default position as well.

This feature depends on the keep-clear-area experiment.

Video: http://recall/-/aaaaaabFQoRHlzixHdtY/ccvYWU8bJ7EycW396QEijm
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/hvQVa0uXCPm2RoDuadZuCA
Bug: 260871991
Test: Manual, toggle the system property for both cases, see videos
Merged-In: Ie7ae440847c81d0a49ccd56061673d86977b3b64
Change-Id: Ie7ae440847c81d0a49ccd56061673d86977b3b64