osxaudiosrc: Support a device as both input and output

osxaudiosrc: Support a device as both input and output

osxaudiodeviceprovider now probes devices more than once to determine
if the device can function as both an input AND and output device.

Previously, if the device provider detected that a device had any output
capabilities, it was treated solely as an Audio/Sink.  This causes issues
that have both input and output capabilities (for example, USB interfaces
for professional audio have both input and output channels).  Such devices
are now listed as both an Audio/Sink as well as an Audio/Source.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1385>