PipeWire Module: RT

The `rt` module uses the operating system's scheduler to enable realtime scheduling for certain threads to assist with low latency audio processing.

This requires `RLIMIT_RTPRIO` to be set to a value that's equal to this module's `rt.prio` parameter or higher. Most distros will come with some package that configures this for certain groups or users. If this is not set up and DBus is available, then this module will fall back to using RTKit.