software/kvm: fix noVNC access
Since f48a06ec noVNC is broken: the default port for websocket is 5700 + display (and not 5900 + display). Fix this error and add a promise to test websocket.
Since f48a06ec noVNC is broken: the default port for websocket is 5700 + display (and not 5900 + display). Fix this error and add a promise to test websocket.