Deploy our own CDS Hooks Sandbox

[jdjkelly]

Goal

• To have a working copy of the CDS Hooks Sandbox at cds.sero.run
• To have an in-memory R4 FHIR server available for use inside of it (solves a major public issue)
• We can use the examples from the guides and examples at a live URL for use in the Sandbox

Probably makes sense to try to deploy this with Dockerfile. May also make sense to contribute changes back upstream.