[connection] give access to is_internal_session boolean Needed if we are to use this object like we currently do with session. Related to #2503918

[req] drop from_controller on non WebRequest object (Closes #2901079) The `controller` concept is purely a web things. It does not belong to generic `req` object. The `build_url` code is slightly changed to handle that. This probably requires extended cleanup later. This is a barely used and very internal API. No deprecation period