This adds a generic gstreamer codec module based on which other
bluetooth codecs viz. aptX, aptX-HD, LDAC and AAC can be supported.
The GStreamer codec plugins used here themselves depend on the native
codec implementation.
aptX/aptX-HD -> libopenaptx
LDAC -> libldac
AAC -> Fraunhofer FDK AAC
Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/440>