[问题] shadowColor属性传参后续会像color属性支持函数吗? #4411

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Checklist

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• npm test passes
• benchmarks are included
• commit message follows commit guidelines
• documents are updated

Description of change

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问题

比如我想实现下面效果时， 需要将每个部分的shadowColor与它本身的颜色相对应，但是目前shadowColor属性只能设置一种颜色。

期望

shadowColor: string | ((datum: Datum, defaultColor?: string) => string)