Flexiglass uses STL OverscrollEffects

STL is changing how scene overscroll is handled. Instead of custom
solutions, the new approach leverages standard Compose components like
OverscrollEffects (see b/378470603).

For each scene or content, STL generates two OverscrollEffects (one
vertical and one horizontal) that can be directly applied to the
composable that will be translated during overscroll.

These effects should be added to any existing overscrollEffects on the
element.

Video: b/382477212#comment2

Test: manually test on Flexiglass
Bug: 382477212
Flag: com.android.systemui.scene_container
Change-Id: I11ab1754135ae308183135aa113b724ff00cf351