Added elevation animation for dragged bubble snapped back to the stack

Added Z animation for PhysicsAnimationLayout, so when bubble is being
dropped, it returns to it`s stack position reducing elevation to flat
state.

Test: PhysicsAnimationLayoutTest
Fixes: 301266186
Flag: N/A
Change-Id: Id179de36348ed0f056a18cda53e3db5dc32cb4ae
3 files changed