Track OverviewToHomeAnim with StateManager

This way we mark the the current state as NORMAL at the start of
the animation, and cancel it as part of other state transitions.
This allows us to interact with launcher (e.g. to go to all apps
or pull down the notification shade) during the animation.

Also use OverviewToHomeAnim from RecentsView#startHome() to
ensure the animation is consistent, e.g. doesn't fade out
RecentsView, scrolls to page 1, etc.

Bug: 144170434
Change-Id: I5348565b9e705d8ffba39818dde9efe82b16bb7a