Alter which tags are added to files

[ProfMoo]

Hi! Thanks for all the work on this project and with gazelle-origin. These projects are looking to be a lifesaver for my music collection.

I've opened this PR because this change solves an issue I've been facing with albumdisambig. Further, I believe the new behavior is closer to the desired behavior. Basically, I'd like for the originquery plugin to add the albumdisambig tag to the files when it's listed in originquery.tag_patterns. Currently, originquery will only add that tag when it's included in the musicbrainz.extra_tags config block. If albumdisambig is added to that block, there can be unintended downstream effects on the musicbrainz plugin (and generally it's not desired that originquery configuration is "hidden" in musicbrainz configuration). For example, the import breaks if origin.yaml doesn't have the "Edition":

beets-beets-1  |   File "/usr/local/lib/python3.8/site-packages/beets/autotag/mb.py", line 498, in match_album
beets-beets-1  |     key = FIELDS_TO_MB_KEYS[tag]
beets-beets-1  | KeyError: 'albumdisambig'

To illustrate, here is my case study of the current behavior:

---

I'm attempting to import two versions of Adele's 30. The origin.yaml files provide the correct "Edition" field across both releases. For the original, "Edition" is blank. For Target exclusive, origin.yaml contains "Edition": Target Exclusive. So far so good. However, if I run a beet import with this config:

musicbrainz:
  extra_tags:
    - year
    - catalognum,
    - country,
    - label,
    - media

originquery:
  use_origin_on_conflict: yes
  origin_file: origin.yaml
  tag_patterns:
    media: '$.Media'
    year: '$."Edition year"'
    label: '$."Record label"'
    catalognum: '$."Catalog number"'
    albumdisambig: '$.Edition'

Beets doesn't add the albumdisambig tag during autotagging. It's skipped over because albumdisambig isn't in musicbrainz.extra_tags. As such, the albums are missing the albumdisambig entirely and the files end up in the filesystem like:

30 (<backup_disambiguator>)
30 (<backup_disambiguator>)

But what I want is:

30 (<backup_disambiguator>)
30 (Target Exclusive)

---

I'd like the "Edition" field to populate those parentheses (through albumdisambig). The change in this PR fixes this issue by attempting to tag the files if it's in the originquery.tag_patterns config block. This also opens up the possibility for additional tags based on origin.yaml, if that's desired.

I've testing this change against a few dozen albums and everything works as I'd expect.

[ProfMoo]

@x1ppy Have you gotten a chance to take a look at this?