ESPAsyncWebserver basic ArduinoJSON handler example

server.on("/api/test", HTTP_GET, [](AsyncWebServerRequest *request) {
      // Respond with JSON {"status": "ok"}
      AsyncResponseStream *response = request->beginResponseStream("application/json");
      DynamicJsonDocument json(1024);
      json["status"] = "ok";
      serializeJson(json, *response);
      request->send(response);
});