refactor(MM): Move ComposableMotionValue to mechanics lib (1/2)

This change graduates the composable wrappers for MotionValue from the
staging sample to a new composable package within the core mechanics
library.

Test: Manually tested on the demo app
Bug: 419520966
Flag: com.android.systemui.scene_container
Change-Id: I2dff45af0472bfcc1abb28a008ccb45289b3cace