System status event animation polish (1/n)

First part of polishing the system status event animations.

- Define a new type `BackgroundAnimatableView` that allows the chip
  animation controller to animate the bounds of the chip
- Define a `ViewCreator` type to simplify some args
- Rework the animation to do simple alpha transition and animate the
  width of the chip rather than translationX
- Variuos other quality of life fixes

Test: manual
Bug: 187881849
Change-Id: I22b7defb8c055a05ac26d0d9e4aa688e120220aa