Sometimes call never transitions out of "idle" state

[mdwelsh]

After creating a VoiceSession and calling ".start()" on it, sometimes we never get a message saying that the session has transitioned from "idle" to "thinking" state. Hence the call is hung and we never get a welcome message from the agent.

Related: If we .stop() the session when it's in this state and call .start() again, it looks like it never tries to reconnect (either to the websocket or the room). So there is a client-side bug there (which I will fix).