[Flexiglass] Send all touches through the NSSLC TouchHandler

Keep sending all the touch events through the NSSLC TouchHandler, let it decide whether the it needs to be dispatched to the individual TouchHandlers, or whether it needs to be ignored due to a drag.

Bug: 359957196
Test: Interact with the Notification stack.
Flag: com.android.systemui.scene_container
Change-Id: I4a6c3f39edda8f7d9aef2eb87bd45f7026bd26c4