Add TaskPositioningController

The CL creates new TaskPositioningController class which lives over the
process WindowManagerService's life time and handle task positioning
tasks like resizing or moving by drag.

Bug: 64149458
Test: atest com.android.server.wm.TaskPositioningControllerTests
Change-Id: I65b3226ce5fa93c16037671ab9cd3b3d84d8f274