Add a stream prober

It will listen to a stream and export metrics on connection quality
and audio to Prometheus.
3 jobs for v2 in 4 minutes and 50 seconds
latest
Status Job ID Name Coverage
  Build Pkgsrc
passed #7445
build_pkgsrc:stretch

00:00:22

 
  Build Pkg
passed #7446
amd64
build_pkg:stretch:amd64

00:01:26

passed #7447
arm64
build_pkg:stretch:arm64

00:04:28