✨ [Feature]: Please provide BackTop component

[kagol]

What problem does this feature solve

可以考虑基于 Floatbar 做功能增强。

What does the proposed API look like

可以参考ElementPlus：https://element-plus.gitee.io/zh-CN/component/backtop.html

[zxlfly]

认领BackTop组件

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

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Claim the BackTop component

[kagol]

认领BackTop组件

欢迎欢迎~

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

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Claim BackTop component

Welcome welcome~