Phase 5: Add fully-featured fhir namespace

[aleksa-krolls]

See parent issue #887 for details.

• Import the fhir v4 adaptor
• Re-export basically all of it through the fhir` namespace. So we should be able to do this:

fhir.create(builders.patient({ identifier: $.patient.id })

• Remove the fhir.utils file (any fhir utils should just go in fhir.js)

The adaptor should use state.configuration.instanceUrl as the base url for all fhir requests, and should handle auth consistently. I am not totally sure how that will work against the wrapped fhir functions yet.

Include a fhir.request function to make an arbitrary request against the fhir root of the isntanceurl. Do not add get/put/etc helpers.

I think the fhir builders should use the root namespace, so builders.patient, and not the fhir namespace, fhir.builders.patient. Just because it's really annoying

[martalovescoffee]

@hunterachieng could you please add an estimate to this issue?