Perform name matching locally

[lumisota]

This isn't great code, but this is a first pass at performing name matching locally, rather than via the Datatracker API. I've kept "names" distinct from "identifiers" because they aren't necessarily unique (whereas identifiers are treated as unique).

person_with_name_email is essentially person_from_name_email from DatatrackerExt, but modified to look for names in the participant database, rather than the Datatracker. The matching is essentially the same (though not exactly), and still relies on hitting an exact match -- good enough for now, but something that can be tweaked.