feat: add search-bar for doc mode, https://github.com/umijs/dumi/issues/373

[suedar]

🤔 这个变动的性质是？/ What is the nature of this change?

• [☑️] 新特性提交 / New feature

🔗 相关 Issue / Related Issue

https://github.com/umijs/dumi/issues/373

长这个样子，覆盖了原来的样式， 仅支持 pc 版本，mobile 版本保持原样

📝 更新日志 / Changelog

Language	Changelog
🇺🇸 English	add search-bar for doc mode
🇨🇳 Chinese	为 doc mode 添加搜索框

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[codecov[bot]]

Codecov Report

Merging #678 (b3c21d7) into master (5656c82) will decrease coverage by 0.33%. The diff coverage is 33.33%.

:exclamation: Current head b3c21d7 differs from pull request most recent head 4680a8c. Consider uploading reports for the commit 4680a8c to get more accurate results

@@            Coverage Diff             @@
##           master     #678      +/-   ##
==========================================
- Coverage   94.17%   93.83%   -0.34%     
==========================================
  Files         112      112              
  Lines        2453     2467      +14     
  Branches      795      799       +4     
==========================================
+ Hits         2310     2315       +5     
- Misses        139      148       +9     
  Partials        4        4              

Impacted Files	Coverage Δ
...ackages/theme-default/src/components/SearchBar.tsx	46.42% <31.25%> (-16.08%)	:arrow_down:
packages/theme-default/src/components/SideMenu.tsx	87.50% <40.00%> (+0.65%)	:arrow_up:

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[PeachScript]

感觉 UI 可以优化下，大家一起看看：

1. 侧边栏的拥挤程度已经很高了，搜索框是不是默认收起会好一些，或者有没有更好的布局方案，哪怕大刀阔斧一些
2. 搜索的结果替代侧边栏子项的方式会比较奇怪，是不是仍旧采用 popup 的形态会好一些

[suedar]

这样的处理参考自 docz ，或者你们有更好的想法。 popup 会有点奇怪 可能有 header 的时候会比较好一点

[birdycn]

怎么使用搜索呢？？

[xrkffgg]

cc @suedar

[suedar]

有点久了这个，之前的场景是复用原搜索框，由于 mode: doc 没有搜索框，将 mode: site 右上角的搜索框放到 doc 上了。 现在可能有点变化，我有空再看看。

[PeachScript]

❤️ 感谢贡献，dumi v1 不再更新，PR 将会关闭；dumi v2 已发布，欢迎继续参与 dumi 的建设，https://d.umijs.org/