渐变色按钮支持点击态

[guangzan]

当前按钮组件设置 bgColor 为渐变色后，没有点击态。或许我们可以参考 vant 的实现 https://vant-ui.github.io/vant/#/zh-CN/button

[ziqisia]

The bgColor property supports passing an object with the following attributes:{normal: string; active: string; disabled: string;}. The active property defines the style for the click state.