Auth API + Colin API - Load COLIN business on demand

COLIN API
- new endpoint for getting required info that auth needs to create the entity record (including business passcode and email)

AUTH API
- new endpoint for on demand loading colin business affiliation data
- need to be able to affiliate via password and registered office email
- need decision on _**re-fetching this to keep it up to date** (preferred approach)_ vs accepting risk for stale data
- registered office email could change
- password could change
- new branch for verifying passcode in Affiliation.is_authorized for colin companies (may not be needed depending on above)
- reuse the existing `EMAIL` affiliation-invitation flow (magic link to the entity's contact email). Needs the LEAR lookup in `_validate_prerequisites` (`affiliation_invitation.py:225,373-384`) bypassed for `is_loaded_lear=False` entities — fall back to auth-entity data. The contact email comes from COLIN at entity creation - decide whether to re-fetch/refresh it from COLIN when an invitation is sent
- minor updates for is_loaded_lear = False flow changes

### Data Migration team - @Rajandeep98 , @ketaki-deodhar
should update auth data when loading business in lear. Discussion needed. Flipping is_loaded_lear flag / updating details of existing auth entity record should be done as part of their script, but updating email may have consequences

**Note**: Socialize approach with Auth team