[Import] Simplify checking contact type is valid

[eileenmcnaughton]

Overview

[Import] Simplify checking contact type is valid

This builds on other open PRs & ensures we are checking in a sensible way that we are not changing the contact type

Before

Where to start - this is being handled in multiple places

After

The lookupContactID function

1. loads the id from external identifier, if applicable
2. checks the contact type is the same as the saved one & rejects the row if now
3. loads from the dedupe rule if the other failed - note the ContactType is implicit in the dedupe rule load

Technical Details

There is still a lotta code around contact_subtype handling which I'll move over next

Comments

[civibot]

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[eileenmcnaughton]

@monishdeb if you get more time to review then this - or #23473 would be great - I'm making real inroads into getting this stuff into a sane state

[colemanw]

This looks like a sensible simplification & is tested.

[eileenmcnaughton]

yay thanks - building more tests on it all the time