feat(legend): 添加图例的正反选功能

[pearmini]

Checklist

• npm test passes
• tests and/or benchmarks are included
• commit message follows commit guidelines
• docs

Description of change

添加分类图例的正反选功能，参考 #3736

使用方式如下：

// 默认不开启
char.legend({
  // 开启并且设置样式
  radio: {
    fill: 'red',
    stroke: 'yellow'
  }
})

2021-12-28.17.58.06.mov

[github-actions]

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