Add zenuml support to mermaid

https://github.com/cryptpad/cryptpad/issues/1132

www/common/diffMarked.js

@@ -36,7 +36,8 @@ define([
         init: function () {
             require([
                 'mermaid',
-            ], function (_Mermaid) {
+                '/lib/mermaid/mermaid-zenuml.esm.min.js',
+            ], function (_Mermaid, zenuml) {
                 console.debug("loaded mermaid");
                 if (Mermaid.__stubbed) {
                     Mermaid = _Mermaid;
@@ -48,7 +49,7 @@ define([
                     });
                 }
 
-                pluginLoaded.fire();
+                Mermaid.registerExternalDiagrams([zenuml]).then(() => pluginLoaded.fire());
             });
         }
     };

www/lib/mermaid/mermaid-zenuml.esm.min.js

@@ -0,0 +1,11 @@
+define(function(){
+    const n = "zenuml", e = /^\s*zenuml/, o = (t) => t.match(e) !== null, r = async () => {
+        const { diagram: t } = await import("./zenuml-definition-b4b159b2.js");
+        return { id: n, diagram: t };
+    }, a = {
+        id: n,
+        detector: o,
+        loader: r
+    };
+    return a;
+});