Add ContentInfo Type to OpenAPI EndpointDocs.request_body, so docs can test different types of content-type requests.

[jesseandringa]

🚀 Feature Request

Right now Endpoint Docs takes in a request_body =
@DataClass
class RequestBodyInfo:
description: Optional[str] = None
examples: Optional[Dict[str, Any]] = None

This does not allow for any content type. And defaults to what parameters your function accepts.
It would be nice to be able to have a content type so that I could tell the user they can pass application json, and application/msgpack etc. (handling it in a middleware). And provide this information with the request_body, so the user could test out both.