Derive error responses from `Raises` docstring

[fraser-langton]

@api.get(
    "/errors_in_docstring",
    # response={codes_2xx: Error1, codes_3xx: Error2},  <-- not needed
)
def errors_in_docstring(request, code: int):
    """
    Raises:
        Error1: error 1
        Error2: error 2
    """
    if code in codes_2xx:
        raise Error1
    if code in codes_3xx:
        raise Error2
    return code, "1"

Not only would it feel more pythonic but when combined with docstring-extraneous-exception (DOC502) and docstring-missing-exception (DOC501) you can do some enforcement that errors are properly documented

[fraser-langton]

Probably would also need something like #941 #1508 implemented first - which seems intuitive but given custom handlers can return anything they want when handling an exception, it isn't as simple as defining the openapi schema from the Exception class?

Similar discussion in fastapi: fastapi/fastapi#9124