Create basic build pipeline for FHIR 4.6.0 <> TS definitions

[jdjkelly]

Goal

Be able to run npm run build and have it build TypeScript definitions for FHIR 4.6.0 and output them to /dist. Would be nice if it globed up descriptions as comments on fields etc.

Open problems

• Can we use Quicktype to convert the 4.6.0 fhir.schema.json to TypeScript? Do we need to use the GraphQL definitions instead?
• Do we need to commit fhir.schema.json? Should we have a download script instead? Maybe doesn't matter right now. More important to just get one working
• 4.6.0 at least (maybe earlier) has a graphql export as well, which is interesting

Attempted solutions

quicktype/quicktype

npx quicktype -s schema ./src/fhir/4.6.0/fhir.schema.json -o dist/fhir.ts

This fails with a stack overflow. Same issue as glideapps/quicktype#1376.

bcherny/json-schema-to-typescript

node attempt-json-schema-to-typescript.js

Hangs. Same issue as bcherny/json-schema-to-typescript#323

PlasmaFHIROrg/TypeScript-FHIR

Doesn't fully run, and exports them to TypeScript classes but this is probably a good start. Something similar to this could work.