Support multiple game sessions and waiting lobby (a la Jackbox)

[Victor-Avelar]

A fix for this issue would have the following behavior:

• Allow players to join an existing session or create a new one
• Utilize join code to group players (and WebSocket clients) into game sessions
• Reject users using the same join code after players exit lobby area and move to map scene
• Coordinate scene transitions via WebSocket server (one person presses "Start Game" button, server sends message to other clients with same game code to initiate scene switch)

[etcadinfinitum]

The current implementation for this fix (see #81) correctly switches scenes and coordinates game sessions for multiple players, but the websocket instance in the client quits when the Maze1 scene starts. Trying to determine the cause and implement a fix may not be possible in the time remaining. I have decided to work on other tasks instead of continuing to debug this.