Allow extra headers

[kliem]

I need to call my github instance with additional custom headers.

E.g. there are authorizations methods that use other headers than Authorization.

[EnricoMi]

This is not possible right now.

Given these headers are specifically need for authorization, the use of Auth should be refactored for your use case.

Instead of (in Requester)

        if self.__auth is not None:
            requestHeaders["Authorization"] = f"{self.__auth.token_type} {self.__auth.token}"

the Auth should integrate like

        if self.__auth is not None:
            self.__auth.authenticate(requestHeaders)

where default implementation would be

    def authenticate(headers):
        headers["Authorization"] = f"{self.__auth.token_type} {self.__auth.token}"

You could then implement your own Auth setting any header that you need for authentication.

Could be combined with #2811

        if self.__auth is not None:
            self.__auth.authenticate(session)