Resolve + Import all FHIR References (beyond just DocumentReference)

[suyashkumar]

We should probably dynamically identify anytime any FHIR resource refers to a binary / file stored elsewhere, and then attempt to retrieve it and store it in GCP / local disk and update the reference url in the FHIR resource. we do this for DocumentReferences already, but should expand to other resources generically if it makes sense.