Botbuilder-js: [PORT] Updates DialogManager to work with skills

[tomlm]

Port this change from botbuilder-dotnet/master branch:
https://github.com/microsoft/botbuilder-dotnet/pull/3709

Fixes #3657

This PR includes the following changes:

• Updated DialogManager to handle skill requests (in addition to parent bot requests). This includes:
  
  
  
  • Handling regular activities sent from the parent.
  
  
  • Handling EoC sent from the parent.
  
  
  • Handling a RePrompt event sent from the parent.
  
  
• Added unit tests.
• Added end to end Parent->Skill sample with DialogManager for testing (under FunctionalTests\Skills\Adaptive).
• Updated code in DialogManager and DialogManagerTests to follow SDK coding style conventions.

I also refactored DialogManager OnTurnAsync in a couple of private methods to split the Skill/Parent processing logic and reduce duplication.

Changed projects

• Microsoft.Bot.Builder.Dialogs.Adaptive
• Microsoft.Bot.Builder.Dialogs.Tests

[R9,Skills]

[stevengum]

@clearab, @gabog is this still for R9 in JS?

[gabog]

I don't think so, this is for adaptive JS and I think that so far the plan is to have JS on parity with R8. Relabeling it to R10

[clearab]

This is actually a duplicate of: https://github.com/microsoft/botbuilder-js/issues/1970