Now that the FHIRcast demo lives in this repo, we should add authorization via the MedplumClient and use MedplumClient.post and MedplumClient.get for making the requests to the server for the FHIRcast routes. This should make it easier for those using MedplumClient to easily utilize FHIRcast with just a few method calls.

Next steps / considerations:

• Add methods to MedplumClient for different FHIRcast flows (what do you think @codyebberson?)
• Write documentation on how to auth without MedplumClient (especially for clients that may be written in other languages, such as the #C/.NET test client for Nuance PowerCast)