HarmonyOS 在cachedir/filedir创建文件夹报错

创建文件使用的是mkdir方法，API使用出现错误，可以参考此篇文档：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-file-fs-V5

同时请参考此Demo

import { fileIo } from '@kit.CoreFileKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { common } from '@kit.AbilityKit';

@Entry
@Component
struct Index {
  @State message: string = 'Hello World';
  private context = getContext(this) as common.UIAbilityContext;
  readSyn = () => {
    let pathDir = "/data/storage/el2/base/files/"
    let newDirPath = pathDir + "/testDir"
    fileIo.mkdir(newDirPath).then(() => {
      console.info("mkdir succeed");
    }).catch((err: BusinessError) => {
      console.error("mkdir failed with error message: " + err.message + ", error code: " + err.code);
    });

  }

  build() {
    Row() {
      Column() {
        Button(this.message)
          .fontSize(50)
          .fontWeight(FontWeight.Bold)
          .onClick(()=>{
            this.readSyn()
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}