Create PFB for each ResearchStudy

[bwalsh]

As an ACED data engineer, in order to make the data ready for Gen3, I need to create a separate PFB for each ResearchStudy

• Create a config file for pfb_fhir
  • See tests/fixtures/**/config.yaml for examples
• It may be useful to write the data in bulk form: .ndjson
• see https://github.com/bmeg/pfb_fhir#usage. for instructions how to run pfb_fhir