async fn claim_linking_mails(
conn: &mut PgConnection,
people: &[&RosterPerson],
linked: &LinkedAccounts<'_>,
course_ids: &BTreeSet<Uuid>,
courses_of_late_completers: &HashMap<String, BTreeSet<Uuid>>,
) -> CreditRegistrationResult<AccountLinkingCodeCounters>Expand description
Claims a linking mail for everyone in people we hold no link for, on each of course_ids or,
for those in courses_of_late_completers, only on the courses their completion is on. Counts
each person once by the strongest claim any course got for them.