Add FHIR <-> CDA converter module

[jenniferjiangkells]

All data generators will generate FHIR data. FHIR data can then be converted to other formats e.g. CDA. Not a new problem space, quite a few proprietary converters, Microsoft has some open-source on this but it's written in Liquid or something.

But you know what? Screw parsers. They're never well-maintained because XML is just a giant pain in the ass and no one would ever voluntarily put themselves through that without a good incentive to. I wrote one 3 years ago, and I know it's full of bugs that I never want to touch again and also I'd rather yeet myself into the sun than look at another CDA.

You know who doesn't get bored? ✨ LLMs ✨ If using LLMs to maintain legacy code isn't a thing yet, it really should be...

This might branch off into a separate project (and maybe a few other features we were thinking about) but let's start here anyway.