feat: multi level sidebar

[WilsonXinxin]

Summary

What kind of change does this PR introduce? (check at least one)

• [ ] Bugfix
• [x] Feature
• [ ] Code style update
• [ ] Refactor
• [ ] Docs
• [ ] Build-related changes
• [ ] Other, please describe:

If changing the UI of default theme, please provide the before/after screenshot:

Does this PR introduce a breaking change? (check one)

• [ ] Yes
• [x] No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• [ ] When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)

You have tested in the following browsers: (Providing a detailed version will be better.)

• [x] Chrome
• [x] Firefox
• [ ] Safari
• [x] Edge
• [ ] IE

If adding a new feature, the PR's description includes:

• [x] A convincing reason for adding this feature
• [ ] Related documents have been updated
• [ ] Related tests have been updated

To avoid wasting your time, it's best to open a feature request issue first and wait for approval before working on it.

Other information: Related issue

[ulivz]

Thanks for your contribution, could you write documentation for this feature?

[WilsonXinxin]

感谢您的贡献，您能为此功能编写文档吗？

I'd love to. Can you tell me where to write and write specifications