PulseAudio UCM support in GNOME

[Bastien Nocera <bnocera redhat com>]

Hey,

A lot of distributions have had to migrate to using UCM for a lot
of devices that previously used hard-coded routing for their codecs,
or just couldn't be supported.

PulseAudio changes and GNOME changes were necessary for this:
https://gitlab.gnome.org/GNOME/libgnome-volume-control/-/merge_requests/10

As libgnome-volume-control is a copylib, it will not get automatically
updated unless a newer version is imported into the repositories that
use it:
https://gitlab.gnome.org/GNOME/gnome-settings-daemon/-/merge_requests/203
https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1444
https://gitlab.gnome.org/GNOME/gnome-control-center/-/merge_requests/843

I'd advise backporting all the GNOME and PulseAudio changes for any
stable distribution.

Regards

---
Bastien Nocera
he/him/his