[Teams] Port of ActionBasedMessagingExtension Fetch Task

[daveta]

Fixes #1197

Description

This matches current C#, if we want to change behavior of how Preview stuff works, we'll change in both..

[coveralls]

Pull Request Test Coverage Report for Build 81968

• 4 of 15 (26.67%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.2%) to 86.539%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/botbuilder/src/teamsTurnContextHelpers.ts	2	13	15.38%

Totals
Change from base Build 81965:	-0.2%
Covered Lines:	4591
Relevant Lines:	5106

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💛 - Coveralls

[stevengum]

Small changes requested... And a question.

[stevengum]

@daveta, can you try to incorporate the fallback scenario that we discussed with Andrew? Checking if a bot is a member of the current channel/conversation and either sending a proactive message or sending a card to the compose box?

[EricDahlvang]

How does one check "if a bot is a member of the current channel/conversation"?

[stevengum]

TeamsInfo.GetRoster() :)

[daveta]

@daveta, can you try to incorporate the fallback scenario that we discussed with Andrew? Checking if a bot is a member of the current channel/conversation and either sending a proactive message or sending a card to the compose box?

I've opened #1263 to track this. I'll take a look today.

[stevengum]

To update others who may come to this thread, the getConversationMembers method does not retrieve the bot as it is an app, not a member. Previously provided information was incorrect.