feat: 支持abcjs乐谱渲染

- 添加相关可配置选项
 - 添加渲染与组件注册相关脚本
 - 添加默认cdn配置

layout/includes/third-party/abcjs.pug

@@ -0,0 +1,18 @@
+script.
+    function abcjsInit() {
+        function abcjsFn() {
+            for (let abcContainer of document.getElementsByClassName("abc-music-sheet")) {
+                ABCJS.renderAbc(abcContainer, abcContainer.innerHTML, {responsive: 'resize'});
+            }
+        }
+        if (typeof ABCJS === 'object') {
+            abcjsFn();
+        } else {
+            getScript('!{url_for(theme.asset.abcjs_basic_js)}')
+                .then(() => {
+                    abcjsFn();
+                });
+        }
+    }
+
+    document.addEventListener('DOMContentLoaded', abcjsInit);