Made it easier to use updatable Animators

The existing system is extended such that AnimationProperties
can be easier animated and running animations updated.

As a first sample this animates the scale of the
icons in the shelf.

Change-Id: Ic88e8094d53f37ab13f5e9e00796b63d229a5114
Test: runtest systemui
Bug: 32437839
6 files changed