PipeWire support as audio backend

[tim-janik]

Anklang currently supports ALSA and Jackd as audio drivers. It defaults to using the virtual pulseaudio ALSA driver for playback.
On most systems this is actually a PipeWire compatibility module , called "pulse-server" — FOSDEM24 slides.
PipeWire is supposed to replace Jackd for low-latency, professional audio scenarios, see:
https://fosdem.org/2024/schedule/event/fosdem-2024-1988-pipewire-state-of-the-union/

So eventually, we should be able to replace our Jackd driver with a native PipeWire driver — API, this might even be more efficient, e.g. if we could eliminate the ring buffer in the current implementation.

For the future, it'd be interesting to know if there are systems left that can reasonably be expected to have Jackd running but no PipeWire support, for the next 1 to 2 distro cycles that is probably the case for most Ubuntu / Debian derivative.