module-raop: Add support for `auth_setup`
These changes fix device pairing for newer AirPlay2 devices.
Some parts of these changes were lifted from: !1112 (closed) (cc @Programmerino)
Even with this however, while pipewire seems to be streaming something with this, the audio output on the IKEA/Sonos device I've been testing this with has only been a few stutters.
Please give this a try and report your experiences back here.