HarmonyOS 屏幕亮度变化回调

参考设置数据项监听：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-settings-V5#settingsregisterkeyobserver11

代码如下：

import settings from '@ohos.settings';

const context: Context = getContext(this);
settings.registerKeyObserver(context, settings.display.SCREEN_BRIGHTNESS_STATUS, settings.domainName.DEVICE_SHARED, (err, value) => {
  if(err){
    console.error('Failed to get the setting.${err.message}');
    return;
  }
  console.log(`Promise:value -> $ {JSON.stringify(value)}`);
});