Force CROSSFADE rotation when launching from double tap gesture.

When activity transition triggers a rotation change, the starting
window will normally be the top window at the time we try
to select the window animation. However, these layout params won't
have the apps rotation animation set (as the client code will set that
on the real window, not the starting window). Eventually we would
like to add API to specify rotation animation via manifest to solve
this problem cleanly. In the mean time, we can force a specific rotation
animation from the double tap gesture, and clean up some camera
ugliness. We accomplish this by attaching an animation hint to
ActivityOptions.

Bug: 28838855
Change-Id: If052cd8cbae76651da43f3b4c590cd9dcc1afc0f