Update Python invoker such that the function being written doesn't depend on flask's response object to return an http status

[andrew-su]

Feature Request

Update the Python invoker to handle http status codes. The way to do it currently is to return a Flask.Response object which makes us a leaky abstraction. We want to perhaps update the response we expect from the function to be (status_code, body) or the likes. We need to also consider the situation where we may want to have attributes returned in the case of CloudEvents or whether we want to respond with a specific header.