breaking changes: cdn 可一鍵設置 本地文件/可單獨配置主題文件，第三方文件的 cdn

breaking changes: 移除 utterances，giscus， addtoany， busuanzi 的 cdn 配置

layout/includes/third-party/math/katex.pug

@@ -1,6 +1,6 @@
-link(rel="stylesheet" type="text/css" href=theme.CDN.katex)
-script(src=url_for(theme.CDN.katex_copytex))
-link(rel="stylesheet" type="text/css" href=theme.CDN.katex_copytex_css)
+link(rel="stylesheet" type="text/css" href=theme.asset.katex)
+script(src=url_for(theme.asset.katex_copytex))
+link(rel="stylesheet" type="text/css" href=theme.asset.katex_copytex_css)
 script.
   (() => {
     document.querySelectorAll('#article-container span.katex-display').forEach(item => {

layout/includes/third-party/math/mathjax.pug

@@ -37,7 +37,7 @@ script.
     }
     
     const script = document.createElement('script')
-    script.src = '!{theme.CDN.mathjax}'
+    script.src = '!{theme.asset.mathjax}'
     script.id = 'MathJax-script'
     script.async = true
     document.head.appendChild(script)

layout/includes/third-party/math/mermaid.pug

@@ -18,7 +18,7 @@ script.
       }
 
       const loadMermaid = () => {
-        window.loadMermaid ? runMermaid() : getScript('!{theme.CDN.mermaid}').then(runMermaid)
+        window.loadMermaid ? runMermaid() : getScript('!{theme.asset.mermaid}').then(runMermaid)
       }
 
       window.pjax ? loadMermaid() : document.addEventListener('DOMContentLoaded', loadMermaid)