Add a config option to exclude pseudo-releases

[emiham]

Ref: #5004 #6180

The mbpseudo plugin documentation says:

The mbpseudo plugin can be used instead of the musicbrainz plugin to search for MusicBrainz pseudo-releases during the import process, which are added to the normal candidates from the MusicBrainz search.

To me this makes it sound like the musicbrainz plugin does not include pseudo-releases, but this is not true. I'd like to fix this, but I'm not sure of the best way to do this. I can think of a few options:

1. Don't include pseudo-releases at all with the regular musicbrainz plugin, and refer to mbpseudo for people who want them
2. Add a config option to exclude all pseudo releases
3. Include pseudo-releases in the normal results (the current behavior), but clearly specify that they are pseudo-releases
4. Clarify how pseudo-releases work in the documentation for the musicbrainz plugin, and explain why you might want to use mbpseudo instead

I don't have a strong opinion on which way would be better, but I do think there should be a way to exclude pseudo-releases. With the mbpseudo plugin I feel like it would be more intuitive to not include them at all with the musicbrainz plugin, but this would probably confuse some users and break their workflows, so I'm reluctant to change the default behavior.

Ping @asardaes @snejus since you worked on mbpseudo: what are your thoughts?

[asardaes]

See #6255

The goal wasn't to separate pseudo-releases into their own plugin, it was to proactively search for pseudo-releases with translations/transliterations when the initial search yields a normal official release.

For reference, the current version will merge some metadata from the pseudo-release and the official one, but will still yield the pseudo-release if that's what it found:

beets/beetsplug/musicbrainz.py

Line 799 in 573dca6

return _merge_pseudo_and_actual_album(release, actual_release)

I imagine it would be possible to let users give more priority to the official releases instead.

[emiham]

Thanks for the explanation and link! That makes it clear that option 1 is off the table.

After giving it some more thought, I think the best option is to add a config setting to exclude pseudo-releases. As far as I remember it's a goal to have the importer UI be very concise, so I don't think it's appropriate to add another field of information.

Updating the documentation would be good either way, but I will defer that to anyone who uses mbpseudo and has a better understanding of it than me.