Add stripfeat plugin

[ARTINKEL]

Description

Adds new plugin stripfeat, which allows the user to automatically replace the featuring artist token in the artist metadata tag with a delimiter of their choice.

This is particularly useful when using beets in conjunction with something like Jellyfin, which expects multiple artists to be formatted in a certain way, and will create separate artists for every feature combination otherwise.

Example

A song with artist metadata underscores feat. Jane Remover would become underscores;Jane Remover.

To Do

• Documentation. (If you've added a new command-line flag, for example, find the appropriate page under docs/ to describe it.)
• Changelog. (Add an entry to docs/changelog.rst to the bottom of one of the lists near the top of the document.)
• Tests. (Very much encouraged but not strictly required.)

[whyman]

Your problem is fixed in the next release of jellyfin, where if you enable "prefer ARTISTS" it will use ALBUMARTISTS, which is populated as a multi-value tag and parsed cleanly.

Obviously that doesnt help you with the current release, but FYI.

[snejus]

@ARTINKEL is this still relevant or you've upgraded to the new release?