httpd: Support user_ctx in websocket handler callback request

Closes https://github.com/espressif/esp-idf/issues/6538

components/esp_http_server/src/esp_httpd_priv.h

@@ -77,6 +77,7 @@ struct sock_db {
     bool ws_close;                          /*!< Set to true to close the socket later (when WS Close frame received) */
     esp_err_t (*ws_handler)(httpd_req_t *r);   /*!< WebSocket handler, leave to null if it's not WebSocket */
     bool ws_control_frames;                         /*!< WebSocket flag indicating that control frames should be passed to user handlers */
+    void *ws_user_ctx;                         /*!< Pointer to user context data which will be available to handler for websocket*/
 #endif
 };