HarmonyOS TextArea在onDidDelete中改变值时，双向绑定不起作用

可以使用@Watch来监听删除事件并设计相应的逻辑，简单示例代码如下：

@Entry
@Component
struct Index4 {
  @State @Watch('del') text: string = '测试'
  controller: TextAreaController = new TextAreaController()
  @State textDel: string = ''

  aboutToAppear(): void {
    this.textDel = this.text
  }

  del() {
    if (this.text.length < this.textDel.length) {
      console.log(`模拟删除回调`)
      if (this.text.length === 0) {
        this.textDel = ''
      }
    } else {
      this.textDel = this.text
      console.log(`textDel: ${this.textDel}`);
    }
  }

  build() {
    Column({ space: 20 }) {
      Text(this.text)
      Text(this.text.toString().length.toString())
      Text('再点击一次删除键')
        .visibility(this.text.length <= 0 ? Visibility.Visible : Visibility.Hidden)
      TextArea({ text: $$this.text, placeholder: 'input your word...', controller: this.controller })
        .placeholderColor(Color.Grey)
        .placeholderFont({ size: 14, weight: 400 })
        .caretColor(Color.Blue)
        .width(300)
    }.width('100%').height('100%').justifyContent(FlexAlign.Center)
  }
}