Fix realtime connection fields

[sacOO7]

• Fields available to use => Connection id, key and recoveryKey.
• Fixed How do we get connectionId from connection? #502

[ttypic]

Thanks, Sachin. It works well. However, I don't really like that we've changed existing fields to async props, even if these fields never worked properly.

I think we should either create new async methods with different names as a workaround in the Connection instead or come up with a solution for making them work as fields (similar to state).

[maratal]

I'm not sure what is happening in this PR since as I said I'm not familiar with the flutter codebase, but can't id be set on .connected event? I believe I've seen this handler.

[sacOO7]

Marking as resolved, since it's already fixed as a part of #505