* Optimize settings form and remove deprecated options
* Update required version to 2.22.0 in theme.yaml
The minimum required version for this theme has been updated from 2.20.0 to 2.22.0 to ensure compatibility with newer dependencies or features.
* Update icon rendering to use icon.value property
#### What type of PR is this?
/kind improvement
#### What this PR does / why we need it:
对 toc 进行优化。
1、当文章不存在 h1、h2、h3、h4 标题时，去除 toc 目录。
2、删除不正确的 activeClass 设置并添加 `active-li` 的样式
#### Which issue(s) this PR fixes:
Fixes#87
#### Does this PR introduce a user-facing change?
```release-note
优化 Toc 选中样式，当文章不存在目录时，删除空目录。
```
