[multi-shade] Launcher touch integration

Fixes multi-shade touch interaction on launcher. NPVC will now
refrain from hiding NotificationShadeWindowView as long as
multi-shade is expanded.

Bug: 274828736
Flag: DUAL_SHADE
Test: additional MultiShadeMotionEventInteractor test cases forthcoming
Test: manually verified dragging down and up on launcher expands & collapses multi shade as expected
Change-Id: I14446b06e87258379f67c6643410e3f4125d0ede