fix: ensure independence of metadata / linking config

[librarianmage]

I realized I made a mistake in #26's logic where adding metadata would happen if match_metadata was False, match_metadata_name was directly set, and link_transactions was True. This PR fixes that logic and adds a test to ensure that the two sets of options don't accidentally enable each other.

[redstreet]

Thanks for catching this. Merged. I'll test it out in the next few weeks on my personal journal before making a release.