feat: add katex options support

[Shimogawa]

Add KaTeX options support in config file and headers! 🥵🥵🥵

[vercel[bot]]

This pull request is being automatically deployed with Vercel (learn more).
To see the status of your deployments, click below or on the icon next to each commit.

hexo-theme-yun – ./

🔍 Inspect: https://vercel.com/yunyoujun/hexo-theme-yun/5aToTQUSYMzdH6G6LYbQvxzwUpav
✅ Preview: https://hexo-theme-yun-git-fork-shimogawa-feat-katex-opts-yunyoujun.vercel.app

hexo-theme-yun-docs – ./

🔍 Inspect: https://vercel.com/yunyoujun/hexo-theme-yun-docs/GQBzLqQQupyaKfugZYU4Rqg1uvFJ
✅ Preview: https://hexo-theme-yun-docs-git-fork-shimogawa-feat-ka-357c59-yunyoujun.vercel.app

[YunYouJun]

Thanks for your contribution.