Implement ActivityHandler correctly in DialogBot

Is your feature request related to a problem? Please describe.
DialogBot inherits from ActivityHandler but the OnTurnAsync method never calls it's base member. There is also the RouterDialog inherited by Main which appears to be doing much the same job as the AcitivityHandler.

Describe the solution you'd like
Either inherit DialogBot from IBot and cut out the unused inheritence or remove the RouterDialog and shift the bulk of the logic from Main into a __Bot class.

Describe alternatives you've considered
Or even remove the router/handler element entirely and allow the active dialog to handle events in context such as responses to adaptive cards.

Additional context
Currently both the ActivityHandler and RouterDialog fail silentliy for unsupported Activities. This is particularly an issue around Teams Authentication where the events are never reaching the appropriate OAuthPrompt.

[faragab]

Sxb I vtdjv