Re-introduce camera_device type

camera_device was previously removed in AOSP commit: b7aace2d
"camera_device: remove type and add typealias" because the
same domains required access to both without exception, meaning
there was no benefit to distinguishing between the two. However,
with the split up of mediaserver this is no longer the case and
distinguishing between the camera and video  provides a legitimate
security benefit. For example, the mediacodec domain requires access
to the video_device for access to hardware accelerated codecs but does
not require access to the camera.

Bug: 28359909
Change-Id: I8a4592722d8e6391c0e91b440914284b7245e232