Eventually think of using GStreamer instead of CPAL as a backend for greater compatibility

[marin-m]

The Rust CPAL uses libasound2/ALSA as a backend which has turned to cause issues with compiling SongRec for Snap, etc.

• See https://crates.io/crates/gstreamer-audio + https://crates.io/crates/gstreamer

[marin-m]

Perhaps we should switch to something else than GST: cpal seems to natively support pulse + pipewire in the recent Git trunk; the GStreamer API is a bit complicate to use; also we should re-evaluate libs for the file decoding part