Add "animation" class to vr_hwc

Add the "animation" class to the vr_hwc service, which is the main
noticeable difference between the service declaration for vr_hwc and the
service declaration for the normal hardware composer service. Hopefully
this will fix the service teardown ordering issue that causes surface
flinger DEAD_OBJECT crashes when Android soft reboots.

Bug: 65555465

Test: I failed to directly reproduce the crash, so can't confirm the
change actually fixes the issue. I tested normal vr usage to confirm
this CL doesn't break anything.

Change-Id: I60e1ad56772c19a76ca3387ad2465a42eef03581
(cherry picked from commit f55a6916a7c92aced005f10f24f50561095b93cc)