Allow animation movie for "find the sensor" flow

This adds an optional overlay to specify a per-device
movie to illustrate enrolling a fingerprint. To enable,
create a new layout overlay for
fingerprint_enroll_find_sensor_graphic.xml using
FingerprintLocationAnimationVideoView

Fixes bug 22954305

Change-Id: I59294f71617ecf7a9bf09603fc0b068cc5aa8ff9