Bug fixes for OAuthCard & Teams, and Task.Run

[Jeffders]

Address these two issues:

#1236
...Use OpenUrl for'msteams' SignIn card instead of SignIn CardAction

#1273
...Properly run the task in the background

[cleemullins]

LGTM. As soon as the build passes, I'll merge this in.

[coveralls]

Pull Request Test Coverage Report for Build 47935

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 23 unchanged lines in 1 file lost coverage.
• Overall coverage remained the same at 67.97%

---

Files with Coverage Reduction	New Missed Lines	%
/libraries/Microsoft.Bot.Builder/BotFrameworkAdapter.cs	23	15.59%

Totals
Change from base Build 47934:	0.0%
Covered Lines:	3408
Relevant Lines:	5014

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💛 - Coveralls

[clearab]

@cleemullins @Jeffders Why this switch away from SignIn action? That should work just fine, shouldn't it?

[EricDahlvang]

@clearab this is an old pr. I think the current code in master is using ActionTypes.Signin and it is working: https://github.com/microsoft/botbuilder-dotnet/blob/master/libraries/Microsoft.Bot.Builder.Dialogs/Prompts/OAuthPrompt.cs#L332

new CardAction
{
    Title = _settings.Title,
    Value = link,
    Type = ActionTypes.Signin,
 },

[RohanSaini]

I am using node js. Still, the sign-in card is not working on teams. I even tried the Microsoft git repo example https://github.com/microsoft/BotBuilder-Samples/tree/master/samples/javascript_nodejs/24.bot-authentication-msgraph
How to resolve this?