OpenAPI models from python typing

It would nice to be able to generate models from the Typing for Swagger/OpenAPI instead of the empty model currently used.

The issue provides no file, test, or entry point; begin by locating the existing empty model used for Swagger/OpenAPI generation and the code that inspects Python typing. Define how typed annotations should map to generated models, then add coverage showing that the generated OpenAPI models are no longer empty.

Written by the indexing model from the issue text.