Get member changes for Teams

[clearab]

Adding roster change with no alterations to the IConversations interface. Calling getMember would require a downcast from an object of type IConversations. See line 78 of TeamsInfo.cs for an example of what this looks like.

This PR includes:

• Adding support for the get single member endpoint to the Conversations object
• Adding support for get single member endpoint to the TeamsInfo object
• Adding support for getting paged members to the TeamsInfo object

Also fixed the formatting in ConversationsExtensions, because reasons.

Resolves #3447

[vman]

Hi @clearab, just curious why the GetConversationMemberAsync function wasn't added to the IConversations interface itself instead of requiring a downcast to the Conversations class like you mention?

[clearab]

@vman We couldn't add it to IConversations because of our strict backwards-compatibility requirements (it would break anyone who was implementing the interface). We talked about quite a few different options for where this should live and settled on this as the least disruptive and most discoverable option. I'd love any feedback on the implementation choice!