STL support of motion spatial and effects animation specs 1/2

This change includes:
- Refactoring SceneTransitions to support both motion spatial and
effects animation specs.
- Removing unused SpringSpec from TransformationSpec.

Test: atest SceneTransitionLayoutTest
Bug: 374893616
Flag: com.android.systemui.scene_container
Change-Id: Id774d683e765777119f921732def4282041ee643