Use the name provided by musicbrainz rather than the ALBUMARTIST tag

[cquike]

This PR is a potential solution for #3833 . It basically sets the name that musicbrainz provides when creating a new album artist.

I don't find this solution particularly elegant for a couple of things:

1. It duplicates code that is found in function check_mbid().
2. It assumes that the musicbrainz plugin is enabled. However this is already the case for check_mbid() function, so maybe it is the time to promote the plugin to be part of the core, since ampache already relies on musicbrainz metadata extensively for its correct behaviour.

Maybe this can be merged for the time being to fix the bug, but in the long run it is probably better to refactor the logic when creating a new artist to avoid a cleaner code.

BTW, other possibility to solve #3833 is to "properly" parse the ALBUMARTIST tag. However I find that prone to error the general case. If no mbid are available then that's the only option, but if mbid do exist then I think the best option is to rely on a proper musicbrainz query.

[codeclimate]

Code Climate has analyzed commit 5d6fdee and detected 2 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Clarity	1
Complexity	1

View more on Code Climate.

[lachlan-00]

might be a good first ampache7 change to enforce use of musicbrainz data over the tags when available. i can rework the lookup data into a separate area/reduce it

i'm going to shift a few things around next week but i might move this to patch7 when i start the branch (hopefully next week)

[lachlan-00]

merging into 7 now. we'll make musicbrainz more important in that branch