Add the IdentifierType UUID to the patient identifer type field

Currently the identiferType in OpenMRS is used to populate the Identifier.type field in FHIR, but only with the name property. This is done here.

We should expand this so that we not only set the text property, but also the Identifier.type.coding.code value to the UUID of the identifierType to allow this to be used by clients where applicable.