Add AcoustID ItemKeys

[Serial-ATA]

There are two tags for AcoustID:

• The ID itself: https://picard-docs.musicbrainz.org/en/appendices/tag_mapping.html#acoustid
• And the fingerprint: https://picard-docs.musicbrainz.org/en/appendices/tag_mapping.html#acoustid-fingerprint

Both of which can appear multiple times.