HDX-10120 Type annotation changes

[IanHopkinson]

This PR includes changes to adapt the HDX HAPI app to cope with new datetime type annotations. Mainly this is replacing sqlalchemy.NaiveDateTime with datetime.datetime, and also sqlalchemy.DateTime. Using NaiveDateTime for response annotation rejects datetimes with time zone information and the new type annotation add time zones by default.

Some endpoints used NaiveDatetime in their query parameter definitions, these were replaced and commented code was removed too. It is also found in the util.py file for definition of the ReferencePeriodParameters class

The majority of changes were in the response models where NaiveDateTime was used widely but not universally. Replacing these with datetime.datetime does not change OpenAPI documentation.