Move global touch handling from SceneContainer to SceneWindowRootView

SceneContainer isn't the best place to forward touches to the
FalsingCollector and other code that needs to know about all touches --
it doesn't see all touches on NSSL, but it does see some touches that
NSSL explicitly chooses to forward, and some of those have a synthetic
ACTION_DOWN instead of their original ACTION_MOVE.

SceneWindowRootView, however, is a great place -- it sees every touch
before NSSL or SceneContainer gets a hand on them, and can thus call
FalsingCollector.onTouchEvent and .onMotionEventComplete before and
after all other touch handling.

Bug: 330492016
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT
Test: manual: post many notifs and tap notif shelf on LS, generally monkey around on LS
Change-Id: Ifc2e2f9a2b65df96d012093112ea51ce34172845