[flexiglass] Handle HUN touch when touches are dispatched to NSSL

In flexiglass, we need HeadsUpTouchHelper to correctly handle HUN gestures when the HUN doesn't have an onClick and the gesture gets distpached to NSSL.

Bug: 371235563
Test: Manually verified dragging on HUN to expand shade works with both clickable and non-clickable HUNs
Test: ExpandShadeFromHun e2e test passes with both flexiglass on and off
Flag: com.android.systemui.scene_container
Change-Id: If25b4d3c2e6be1bbd0f8581f480915f9f6cfb667