Display.ElementSelected comes with a session object

[ThomasI81]

I found a inconsistent behaviour in the SpeechletService when handling the DisplayRequest.
Unfrotunately I don't have a good idea how to deal with it... so far.

The DisplayRequest is derived from ExtendedSpeechletRequest which is correct as it provides a type and a subtype. SpeechletService::ProcessRequestAsync(...) either handles ExtendedSpeechletRequests without
a Session object (which is also correct in terms of https://developer.amazon.com/de/docs/custom-skills/request-and-response-json-reference.html#request-body-parameters) or as an SpeechletRequest with Session object.

The problem is, that the Display.ElementSelected Event from Amazon comes with session information in the original JSON, it's correctly parsed but finally lost inside ProcessRequestAsync(..).
(It's not clearly stated in https://developer.amazon.com/de/docs/custom-skills/display-interface-reference.html#touch-selection-events)

Maybe someone has a good idea how to deal with it!