Minimal functionality for use in {beekeeper} 0.1 (first checkpoint). That checkpoint:

0.1.0: Basic authentication and endpoint calls.

• Export a function to generate R/.R and tests/testthat/.R files to authenticate the user and make a call to the API, given the URL of an OpenAPI spec in YAML format. The generated files will follow and encourage best practices, and will serve as the core around which the rest of a package would be built.
• Produce a vignette about configuring authentication.

Do not worry about making this CRAN-ready for 0.1. I will likely need some more {rapid} development to make it feel CRAN-ready, but that isn't necessary until everything is going to CRAN (probably long after 0.1).