HarmonyOS 实现只需要保留上拉加载更多，但是不需要下拉刷新

Refresh通过参数refreshing判断当前组件是否正在刷新，可以控制该参数变化来触发下拉刷新：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/ts-container-refresh-V5#ZH-CN_TOPIC_0000001930756929__refreshoptions对象说明

demo：

@Entry
@Component
struct RefreshExample {
  @State isRefreshing: boolean = false
  @State arr: String[] = ['0', '1', '2', '3', '4','5','6','7','8','9','10']

  build() {
    Column() {
      Button('刷新').onClick(()=>{
        this.isRefreshing = true
      })
      Refresh({ refreshing: $$this.isRefreshing}) {
        List() {
          ForEach(this.arr, (item: string) => {
            ListItem() {
              Text('' + item)
                .width('100%').height(100).fontSize(16)
                .textAlign(TextAlign.Center).borderRadius(10).backgroundColor(0xFFFFFF)
            }
          }, (item: string) => item)
        }
        .onScrollIndex((first: number) => {
          console.info(first.toString())
        })
        .width('100%')
        .height('100%')
        .divider({strokeWidth:1,color:Color.Yellow,startMargin:10,endMargin:10})
        .scrollBar(BarState.Off)
      }
      .onStateChange((refreshStatus: RefreshStatus) => {
        console.info('Refresh onStatueChange state is ' + refreshStatus)
      })
      .onOffsetChange((value: number) => {
        console.info('Refresh onOffsetChange offset:' + value)
      })
      .onRefreshing(() => {
        setTimeout(() => {
          this.isRefreshing = false
        }, 2000)
        console.log('onRefreshing test')
      })
      .backgroundColor(0x89CFF0)
      .refreshOffset(64)
      .pullToRefresh(true)
    }
  }
}