缩略轴 slider 支持配置位置 #3313

• I have searched the issues of this repository and believe that this is not a duplicate.

What problem does this feature solve?

老版本 slider 通过 interact 创建，可以通过绑定 dom 改变位置。 现在新版本 slider 改成了 option 配置，且默认固定在 图表底部 ，没法调整（比如放到图表上方）：https://github.com/antvis/G2/blob/a143ef54b14f23afc8f443867473a07449400321/src/chart/controller/slider.ts#L112

What does the proposed API look like?

options.direction

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