Animate from local list of WindowStateAnimators.

Stop animate() from using the mWindows maintained by
WindowManagerService. Animating WindowStateAnimators are now drawn from
a HashSet maintained by WindowAnimator and containing just those
WindowStateAnimators that have Surfaces.

When starting a move animation do not place parameters directly into
the WindowStateAnimator, instead pass them through the Handler.

Also removed synchronization points from mWindows/mAppTokens
add/remove.