Emailer - update affiliation processor to work with alternate name changes

Update email processor(s) such that we are able to work with alternate_name entries where required. With the new data model, SPs will need to use alternate_name similar to the way we use a legal_entity record.

**TODOs**
Do following for email processor(s) relevant to this ticket:
- [ ] Do work in legal name branch
- [ ] Update to work with alternate names and legal entities
- [ ] Update versioning logic where required. May be still using versioning approach used in old data model
- [ ] There may be some other misc updates required to get processor working. Update as appropriate.
- [ ] Update worker.py as required
- [ ] Update tests relevant to this email processor

Start by locating the email processor(s), their legal name branch, worker.py, and the related tests. Read how legal_entity and alternate_name are represented, then trace the existing versioning logic; done means the processor handles both alternate names and legal entities and the relevant tests pass.

Written by the indexing model from the issue text.