Adding OAuthCard support for Streaming Extensions

[Jeffders]

Description

This adds OAuthCard resolution to connections made with streaming extensions.

Specific Changes

Adds the polling mechanism to retrieve OAuth tokens when an OAuthCard is sent via streaming extensions. This was the approved design, so porting it to the JS bot builder.

Basically:
When an OAuthCard is sent on streaming connection, the BotAdapter begins to poll for that particular token until it is found. The service can override and terminate the polling if need be. Once the token is retrieved, it is sent back through the adapter.

Testing

Added new tests that match the C# implementation.

[coveralls]

Pull Request Test Coverage Report for Build 82770

• 64 of 71 (90.14%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.07%) to 86.987%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/botbuilder/src/tokenResolver.ts	43	45	95.56%
libraries/botbuilder/src/botFrameworkAdapter.ts	9	14	64.29%

Totals
Change from base Build 82763:	-0.07%
Covered Lines:	4743
Relevant Lines:	5240

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💛 - Coveralls

[carlosscastro]

This is a port from a c# PR that we iterated a lot on. Looks good feature wise. Might be good to have some of the folks that regularly work on js to do a pass.

[cleemullins]

Please merge when ready.