Mqtt kafka will message delivery

[bmaidics]

No description provided.

[jfallows]

At the moment, we are modeling session stream abort and close as the same behavior, then special casing close with endEx to handle the different behaviors.

It feels like we are working too hard to get the effect, and could instead take advantage of abort (potentially send will message) vs close (do not send will message), and trigger those accordingly from mqtt binding on session stream.

Potentially no need for mqtt:endEx, use mqtt:abortEx instead if we want to convey exact error code, and close implies normal disconnect.