[Task] Replace direct WebSocket with Vertx SockJS

[andrewazores]

https://vertx.io/docs/vertx-web/java/#_sockjs

https://vertx.io/docs/apidocs/io/vertx/ext/web/handler/sockjs/SockJSSocket.html

SockJS behaves similarly to the WebSocket API, but actually uses WebSocket as one possible underlying transport with other fallback options in case the client does not support actual WebSockets. This should be a generally transparent change, but it increases compatibility with more clients in more network environments.