[Teams] ComposeMessageExtensionAuthBot teams scenario

[EricDahlvang]

Fixes: #1239

[coveralls]

Pull Request Test Coverage Report for Build 81777

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 86.722%

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Totals
Change from base Build 81771:	0.0%
Covered Lines:	4598
Relevant Lines:	5101

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💛 - Coveralls

[stevengum]

Please address Tien's feedback before merging this.

Addressing tsuwandy's feedback is required before this PR is merged.

[tsuwandy]

Thank you Eric!!

[tsuwandy]

Thanks Eric!!

Dismissing ... Tien has approved

[daveta]

I got into the practice of casting (so you get some sense of what each block is) - for example:
public static toComposeExtensionResultResponse(cardAttachment: Attachment) : MessagingExtensionActionResponse {

    return <MessagingExtensionActionResponse> {
        composeExtension: <MessagingExtensionResult> {
            type: 'result',
            attachmentLayout: 'list',
            attachments: [ <MessagingExtensionAttachment> cardAttachment ]

        }
    }
}

[EricDahlvang]

That would be better ... i've just been casting the top level return, but should be casting the fields too, you're right!