`rewrite` plugin "artist" rules should also apply to `artist_sort` and `albumartist_sort`

Currently, rewrite rules to artists only impact the `artist` and `albumartist` fields. Since for latin-script artist names, the `artist_sort` and `albumartist_sort` is usually identical, it makes sense to also apply the rewrite rule sto those fields by default.

Alternatively, it could be a configuration option, if changing this after the fact isn't wanted.