Fix web sockets closing ungracefully

MediaBrowser.Controller/Net/IWebSocketConnection.cs

@@ -58,5 +58,11 @@ namespace MediaBrowser.Controller.Net
         Task SendAsync<T>(WebSocketMessage<T> message, CancellationToken cancellationToken);
 
         Task ProcessAsync(CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// Gracefully closes the socket.
+        /// </summary>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        void CloseSocket(CancellationToken cancellationToken);
     }
 }