Expose optical frame in CameraSensor to be used by DepthCameraSensor#362

iche033 merged 1 commit intogazebosim:gz-sensors7gazebosim/gz-sensors:gz-sensors7from

Levi-Armstrong:fix/DepthCameraSensorLevi-Armstrong/ign-sensors:fix/DepthCameraSensorCopy head branch name to clipboard