Move wallpaper animations int WindowAnimator.

More refactoring. This time wallpaper animations were broken up from
WindowManagerService and the layout piece kept there while the
animation piece was moved into WindwoAnimator.

Also, applyAnimationLocked and applyEnterAnimationLocked were moved
from WindowManagerService to WindowState.

Change-Id: I05935023702ce05fdfdc804342ec14f719cdfea4