[flexiglass] Reimplement closing guts on outside touch in flexiglass

Adds a flow to SceneContainerRepository of whether the flexiglass Compose hierarchy is being touched, and a flow to NotificationViewHeightRepository of whether the current gesture started on an open notification guts. Closes guts when the former is true and latter is false.

Bug: 359956787
Test: unit tests forthcoming
Flag: com.android.systemui.scene_container
Change-Id: Ia9e4831a3897160ad84c143231bb6b1515c27e11