fix(highlightjs): unable to match due to init normalization

packages/commons/src/lib/mime_type.ts

@@ -16,3 +16,14 @@ export interface MimeType extends MimeTypeDefinition {
      */
     enabled: boolean;
 }
+
+/**
+ * Given a MIME type in the usual format (e.g. `text/csrc`), it returns a MIME type that can be passed down to the CKEditor
+ * code plugin.
+ *
+ * @param mimeType The MIME type to normalize, in the usual format (e.g. `text/c-src`).
+ * @returns the normalized MIME type (e.g. `text-c-src`).
+ */
+export function normalizeMimeTypeForCKEditor(mimeType: string) {
+    return mimeType.toLowerCase().replace(/[\W_]+/g, "-");
+}