Entity BN - Update admin flow to work with alternate names(DO LAST)

Update bn processor 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 bn processor(s) relevant to this ticket:
- [ ] Do work in legal name branch
- [ ] Finish up any cleanup work required
- [ ] 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 LegalEntity, AlternateName and Filings model manually in common models to match with legal api models as required
- [ ] Update worker.py as required
- [ ] Update tests relevant to this bn processor