Add document to clarify Best Known Method of user space packages: alsa-lib, alsa-ucm-conf, PulseAudio, GNOME etc.
Based on the document, we'll maintain ‘BKM packages’ based on documented upstream tag + fixes being upstreamed for each program.
The BKM packages would be provided externally as Debian packages as well as source code with a branch for non-Debian distros. This will require the use of clones in thesofproject (as done for alsa-lib already).
See also internal issue GL 221