HarmonyOS 如何获得GMT时区时间

参考下列示例demo：

function formatGtsMTDateToString(gmtDate) {
  const year = gmtDate.getUTCFullYear();
  const month = gmtDate.getUTCMonth() + 1;
  const day = gmtDate.getUTCDate();
  const hours = gmtDate.getUTCHours();
  const minutes = gmtDate.getUTCMinutes();
  const seconds = gmtDate.getUTCSeconds();

  const dateString = `${year}-${formatNumber(month)}-${formatNumber(day)}T${formatNumber(hours)}:${formatNumber(minutes)}:${formatNumber(seconds)}Z`;
  return dateString;
}

function formatNumber(number) {
  return number < 10 ? `0${number}` : number;
}
const dateString = formatGMTDateToString(gmtDate)