WebSocket routing based on message

[assaf]

The idea is to have specific message handler. Maybe:

• socket/action_join.ts for all messages that contain action: "join"
• socket/[room].ts for all messages that contain the property room (any value)
• socket/[room]/action_join.ts for all messages that specify a room and the action "join"
• socket/index.ts is the catch-all