applemedia: Add some properties to GstAvfDevice
Adds properties to the devices listed in GstDeviceMonitor by the applemedia plugin. The device.api property is set to "avf" and everything else is taken directly from the AVCaptureDevice object provided by AVFoundation.
I'm not sure how to name the properties, though. Are there more standard names for any of them?
Also, I have a Mac Mini, which has no built-in cameras, so I can only test the properties that exist for external webcams. There are more properties that could be included, like device type and position.