Add support for autodetecting pipewire sink devices

[virtuald]

pipewire is default on fedora now, and of course it's audio sink is slightly different...

Interestingly enough, on my desktop this isn't needed, but on my laptop audio device selection doesn't work unless this patch is applied.

[luzip665]

Here (Ubuntu 22.04) it works in general.

I need to install gstreamer1.0-pipewire package to see the sink.
Additionally I need to cast device id to string in

exaile/xl/player/gst/sink.py

Line 137 in e58736e

yield (display_name, device_id, device.create_element)

because with gstreamer1.0-pipewire package installed the device id is (int)54, without this package it is "alsa.something"

[virtuald]

I had some issues with devices being restored after rebooting my laptop, so I'll have to look at the properties a bit harder to see if there's one that persists across reboots.

[virtuald]

It appears that there are no stable properties in device.props, but node.name in device.props.properties seems to be intended to be stable (see https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/525). This seems to work on reboot now.