rest of modifications that change how the custom MediaDevice are created/used.
Now it should be possible to create a CaptureDeviceInfo with the respective protocol
of the custom MediaDevice (but ivffile protocol doesn't work, I don't know why).

But the code is legacy : you can still create and use VideoGreyFadinMediaDevice or
IVFMediaDevice as MediaDevice, instead of created a MediaDeviceImpl with a
CaptureDeviceInfo.