feat: pavucontrol in sys-audio

The mixer provided by the program volumeicon is okay, it shows only one
input and one output. Pavucontrol correctly detects the different inputs
and output of each audio client, you can have deeper control of the
client volume.

salt/sys-audio/install.sls

@@ -25,6 +25,7 @@ include:
       - alsa-utils
       - volumeicon-alsa
       - socat
+      - pavucontrol
 
 {% set pkg = {
     'Debian': {