Enable deserialization for OAuthPrompt Dialog With TypeHandling.None

[kvbreddy]

This PR is to provide an option to use safe deserialization (TypeHandling.None) of OAuthPrompt dialog instead of requiring to use TypeHandling.All.

Partially fixes this issue #2437.

Added an extensions method on object which can be used in other places so that other Dialogs can also this for safe deserialization.

   public static T CastTo<T>(this object obj)
    {
        if (obj is T asT)
        {
            return asT;
        }
        else if (obj is JObject asJobject)
        {
            // If types are not used by storage serialization, and Newtonsoft is the serializer
            // the item found can be a JObject.
            return asJobject.ToObject<T>();
        }
        else if (obj is JArray asJarray)
        {
            // If types are not used by storage serialization, and Newtonsoft is the serializer
            // the item found can be a JArray.
            return asJarray.ToObject<T>();
        }
        else if (obj == null)
        {
            return default(T);
        }
        else
        {
            throw new InvalidOperationException("Data is not in the correct format for casting.");
        }

[coveralls]

Pull Request Test Coverage Report for Build 101587

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1258 unchanged lines in 159 files lost coverage.
• Overall coverage decreased (-1.4%) to 78.18%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/Adapters/Microsoft.Bot.Builder.Adapters.Facebook/FacebookAdapterOptions.cs	1	86.67%
/libraries/integration/Microsoft.Bot.Builder.Integration.ApplicationInsights.Core/ApplicationBuilderExtensions.cs	1	71.43%
/libraries/Microsoft.Bot.Builder.AI.LUIS/LuisApplication.cs	1	96.36%
/libraries/Microsoft.Bot.Builder.AI.LUIS/V3/LuisApplication.cs	1	96.43%
/libraries/Microsoft.Bot.Builder.AI.LUIS/V3/LuisUtil.cs	1	96.35%
/libraries/Microsoft.Bot.Builder/BotStateSet.cs	1	85.0%
/libraries/Microsoft.Bot.Builder.Dialogs/Debugging/DebugSupport.cs	1	75.0%
/libraries/Microsoft.Bot.Builder.Dialogs/Debugging/SourceRange.cs	1	46.15%
/libraries/Microsoft.Bot.Builder.Dialogs.Declarative/Resources/ResourceExplorer.cs	1	96.3%
/libraries/Microsoft.Bot.Builder.Dialogs/Prompts/PromptCultureModels.cs	1	97.53%

Totals
Change from base Build 101577:	-1.4%
Covered Lines:	21312
Relevant Lines:	27260

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💛 - Coveralls