Enable ESLint rule unicorn/no-array-for-each, auto-fix all violations, manually address new issues for ~4% time reduction measured via profile-fixture.mjs on Apple Silicon M1.

lib/md027.js

@@ -13,7 +13,7 @@ module.exports = {
   "function": function MD027(params, onError) {
     let blockquoteNesting = 0;
     let listItemNesting = 0;
-    params.tokens.forEach((token) => {
+    for (const token of params.tokens) {
       const { content, lineNumber, type } = token;
       if (type === "blockquote_open") {
         blockquoteNesting++;
@@ -51,6 +51,6 @@ module.exports = {
           }
         }
       }
-    });
+    }
   }
 };