Remove fluff from AdaptiveCardPrompt Sample after SDK merge

[mdrichardson]

PR for AdaptiveCardPrompt Samples

C# AdaptiveCardPrompt relies on a couple of pieces of the Dialogs package that are internal. It's modified a little in the sample so that the sample can stand on its own.

Node AdaptiveCardPrompt is a compiled version of adaptiveCardPrompt.ts and then edited a little for readability.

There are a few comments and some files that will need to be deleted after/if AdaptiveCardPrompt is merged into the SDK -- targeting R8.

Really, it should get a full review, but off-hand it will mostly be:

• READMEs with updated link for both samples
• Delete in AdaptiveCardPrompt in both samples (they'll be in the SDK)
• Ensure all files reference the SDK and not something local, as applicable in both samples
• Delete RemoveOncePromptInSDK/ from C# sample
• Adjust namespaces in C# samples
• Review package.json in node sample

[mdrichardson]

Closing since this is in the Community Repo now