[2/n] Add TilingDividerView and its WindowlessWindowManager

TilingDividerView will be drawn upon tiling tasks left and right in
DesktopMode on SurfaceControlViewHost hosted on
DesktopTilingDividerWindowManager which is a WindowlessWindowManager
utilizing the Display's root leash.

TilingDividerView is mostly a copy of DividerView, with changes to
input handling, accessibility and bounds calculations.

It is necessary to maintain DividerView and TilingDividerView separately
as they will diverge significantly in the upcoming updates, to introduce
rounded corners in a different bounds, current input handling and future
accessibility requirements.

Flag: com.android.window.flags.enable_tile_resizing
Test: tests are WIP, but will mostly be copied from DividerView
Bug: 368878003

Change-Id: I82984d71c998e092e34dcba57f14818a89f61a6a