Enable multi container support

[JannikStreek]

Proposed feature
Currently, the application can't be deployed as multiple nodes / containers as the web socket connections are stored in memory. NestJS/Socket.io feature adapters which can manage this via Postgres or redis which would enable multi container hosting. We should explore these options and, if possible, offer such a deployment as an option. See https://docs.nestjs.com/websockets/adapter and https://socket.io/docs/v4/adapter/ and https://socket.io/docs/v4/redis-adapter/.