Osx hidden device

Set of patches to support hidden devices on macOS

macOS features hidden devices. These are devices that will not be shown in the macOS UIs and that cannot be retrieved without having the specific UID of the hidden device. There are cases when you might want to have a hidden device, for example when having a virtual speaker that forwards the data to a virtual hidden input device from which you can then grab the audio. The blackhole project supports these hidden devices and this patch provides a way that if the device id is a hidden device it will use it instead of check the hardware list of devices to understand if the device is valid.