Support AdaptiveCards in Application object

[rido-min]

to add builder.WithAdaptiveCards()

[rido-min]

Based on the comments on microsoft/Agents-for-net#167 seems dotnet has not completed the implementation of Application.WithAdaptiveCard

I'm trying to understand when/why WithAdaptiveCard is required.

We can also use this task to discuss if we should dictate which channel supports which AC feature.

@MattB-msft ?

[rido-min]

waiting on microsoft/Agents-for-net#288

[rido-min]

completed via #332