Add more properties to sink/source to make them always process and
have the right priorities. Make sure the sink has higher priority than
the source so that we can pull in samples through the graph.
Only trigger the graph cycle when driving the graph.
Make sure to return something from process to signal that the graph can
continue processing.
Makes a device with a source and sink that automatically
proxies all physical ports from jack. Jack then drives our
PipeWire pipeline from its own thread.