HarmonyOS 如何获取Preferences缓存空间大小，以及如何清除Preferences缓存空间

清除Preferences：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-data-preferences-V5#clear

获取本应用存储的Preferences大小：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-file-storage-statistics-V5#storagestatisticsgetcurrentbundlestats9

import { BusinessError } from '@kit.BasicServicesKit';
storageStatistics.getCurrentBundleStats().then((BundleStats: storageStatistics.BundleStats) => {
  console.info("getCurrentBundleStats successfully:" + JSON.stringify(BundleStats));
}).catch((err: BusinessError) => {
  console.error("getCurrentBundleStats failed with error:"+ JSON.stringify(err));
});