audio/abcde: Add MusicBrainz support
- Make MusicBrainz support an on-by-default option
- Add pkg-plist file to allow @sample to be clearly used for the config file
- Include patch from upstream bug#54 to fix calculating MusicBrainz discid [1]
[1] https://abcde.einval.com/bugzilla/show_bug.cgi?id=54
PR: 223346
Approved by: tz (maintainer timeout)