🥳 Improved health sample support, significant refactor of CLI, server…

… and parsing code (#3)

* Adds support for any health sample data type Shortcuts exposes, with additional support for a handful of types and dataclass definitions to easily extend to more types in the future

* Switched to Starlette+Uvicorn for handling HTTP requests from Shortcuts, decoupled parsing logic from CLI/server logic

* Switched to Click for defining the CLI

* Increased testing coverage for supported health sample data types

minor README change for pypi image support