Capture "primary" artist as a separate field

In beets when you have a CD that is "artist featuring artist" there is no way to name the folder as the primary artist. This creates multiple folders and then they dont get imported into tools like lidarr.

Example
Artist - Album - Album Artist
As Is: 2 Chainz Featuring Drake - Big Amount - 2 Chainz Featuring Drake
Proposed: 2 Chainz Featuring Drake - Big Amount - 2 Chainz

If you look at the tags the albumartist MBid is for 2 Chainz.
The MBid for the album is as is
the MBid for release-group is as is.

Beets is handling "Album Artist" for Folder naming from the album artist property. But the Album artist should be the pirmary artist if you want other tools like lidarr to manage this better.

It also creates a bunch of extra artist folders.
Possible option would be to use the FtinTitle plugin and mirror to FtinAlbumArtist


Start by tracing how beets derives folder names from album-artist metadata, then compare that path with the issue's 2 Chainz and Drake example. Review the FtinTitle plugin as the proposed direction and verify the resulting Album Artist and folder names against the stated Lidarr use case.

Written by the indexing model from the issue text.