[Bug] dimension tooltip 不支持双 band 轴

[zamhown]

目前只能识别到一个 band 轴

const spec = {
  type: 'line',
  data: [
    {
      id: 'line0',
      values: [
        { x: 'Round 1', y: 21, c: 'Role A' },
        { x: 'Round 2', y: 28, c: 'Role A' },
        { x: 'Round 3', y: 22, c: 'Role A' },
      ]
    },
     {
      id: 'line1',
      values: [
        { x: 'Round A', y: 38, c: 'Role B' },
        { x: 'Round B', y: 45, c: 'Role B' },
        { x: 'Round C', y: 56, c: 'Role B' },
      ]
    }
  ],
  legends: {
    visible: true,
    orient: 'bottom'
  },
  axes: [
    {
      orient: 'left',
      max: 100,
    },
    {
      orient: 'bottom',
      seriesIndex:[0]
    },
    {
      orient: 'top',
      seriesIndex:[1]
    }
  ],
  series:[
    {type: "line", dataIndex:0, id:'line0',tooltip:{}},
    {type: "line", dataIndex:1, id:'line1',tooltip:{}}
  ],
  xField: 'x',
  yField: 'y',
  seriesField: 'c',
};
const vchart = new VChart(spec, { dom: CONTAINER_ID });
vchart.renderAsync();
// Just for the convenience of console debugging, DO NOT COPY!
window['vchart'] = vchart;