Add FHIR mapping for patient_preferred_language

[DanielSass]

Description

From ReportStream:

patient_preferred_language We're not getting this value in the UP. It should go under Patient.communication.language

We have patient preferred language in both the bulk uploader as an option field and in single entry. We want to map it to the FHIR location mentioned.

Proposed solution

Add FHIR mapping for patient preferred language.

Additional context

https://hl7.org/fhir/R4/patient.html https://hl7.org/fhir/R4/valueset-languages.html