[5/n] Add desktop tiling project skeleton

This CL introduces DesktopTilingDecorViewModel, which manages features requiring
different management for different screens.

This CL also introduces DesktopTilingWindowDecoration, which manages tiling tasks
left and right and initiating the divider resources on a WindowlessWM.

and some helper classes that will help with veiling like TiledTaskHelper
and snap bound calculation helpers.

Flag: com.android.window.flags.enable_tile_resizing
Test: tests are WIP
Bug: 369332590
Change-Id: Id230403818a2261086804fa9125a15d188be20e6