This is hard to do currently because the natural place to do it (and
where the previous seeAlso stuff was done) is translate_item.js, but
with async import translators that now only gets one item at a time,
whereas saving item relations requires all items to be saved. So this
would probably need to be done in the import code in translate.js.
It might also require undoing
https://github.com/zotero/zotero/pull/453 so that getResourceURI() works
on notes and figuring out another solution for the problem that was
trying to solve.