API update for insets

- Rename WindowInsetsAnimationListener to
WindowInsetsAnimationCallback
- Make onAnimation WindowInsetsAnimationCallback.onStarted
hierarchical by giving the client a chance to consume
AnimationBounds, which then will be dispatched to its children.
- Clarify that WindowInsetsAnimationController insets are always
relative to the window.
- Introduce progress variable for inset animations. Since
DecorView will be consuming insets, apps still need a way to
calculate the full progress. Instead of also dispatching the root
insets, we offer a animation progress instead.

Bug: 111084606
Test: CTS will be added in the future
Change-Id: I7df27581d01c1db0118eef469ec089249012ba5f