HarmonyOS 让tabbar居左显示

目前没有api设置，可以使用自定义tabbar实现，demo如下：

@Entry
@Component
struct TabsExample {
  @State tabArray: Array<number> = [0, 1, 2]
  @State focusIndex: number = 0
  @State pre: number = 0
  @State index: number = 0
  private controller: TabsController = new TabsController()
  @State test: boolean = false
  // 单独的页签
  @Builder
  Tab(tabName: string, tabItem: number, tabIndex: number) {
    Row({ space: 20 }) {
      Text(tabName).fontSize(18)
    }
    .justifyContent(FlexAlign.Center)
    .constraintSize({ minWidth: 35 })
    .width(100)
    .height(60)
    .borderRadius({ topLeft: 10, topRight: 10 })
    .onClick(() => {
      this.controller.changeIndex(tabIndex)
      this.focusIndex = tabIndex
    })
  }

  build() {
    Column() {
      Column() {
        // 页签
        Row({ space: 7 }) {
          Scroll() {
            Row() {
              ForEach(this.tabArray, (item: number, index: number) => {
                this.Tab('页签 ' + item, item, index)
              })
            }
            .justifyContent(FlexAlign.Start)
          }
          .align(Alignment.Start)
          .scrollable(ScrollDirection.Horizontal)
          .scrollBar(BarState.Off)
          .width('90%')
        }
        .alignItems(VerticalAlign.Bottom)
        .width('100%')
        .backgroundImage($r('app.media.bg'))
        .backgroundImageSize({ width: '100%', height: '100%' })
      }
      .alignItems(HorizontalAlign.Start)
      .width('100%')

      //tabs
      Tabs({ barPosition: BarPosition.Start, controller: this.controller }) {
        ForEach(this.tabArray, (item: number, index: number) => {
          TabContent() {
            Text('我是页面 ' + item + ' 的内容')
              .height(300)
              .width('100%')
              .fontSize(30)
          }
          .backgroundColor(Color.Pink)
        })
      }
      .width('100%')
      .barHeight(0)
      .animationDuration(100)
      .onChange((index: number) => {
        console.log('foo change')
        this.focusIndex = index
      })
    }
    .height('100%')
  }
}