STL introduces OverscrollEffects [1/2]

STL will generate two OverscrollEffects for each scene: one vertical and
 one horizontal. These effects can be used within the scene to handle
overscroll gestures from the SLT.

Once attached to the scene, the effects can also be used by other
scrollable components to manage their overscroll gesture.

Test: atest OffsetOverscrollEffectTest
Test: atest ElementTest
Bug: 378470603
Flag: com.android.systemui.scene_container
Change-Id: I0c6c19293a9f559a0bb2c366bd1186c6b0ecce21