PriorityNestedScrollConnection: Add flingToScroll [1/2]

A new utility has been added that consumes velocity (either partially or
 fully) and converts it into scroll events.

Test: atest PriorityNestedScrollConnectionTest
Bug: 370949877
Flag: com.android.systemui.scene_container
Change-Id: Ie264b71683dd2d133f98050ee0a1fd86f8d1d743