Resolve #3480037 "Nested menus with"

Closes #3480037

components/02-components/menu/src/menu-aria-controls.js

 (function (Drupal) {
+  /**
+   * Attaches ARIA controls and data attributes to given elements.
+   *
+   * This function iterates over each element in the provided array and sets the appropriate
+   * ARIA attributes based on the element type (button or other).
+   *
+   * For buttons, it sets `aria-haspopup`, `aria-controls`, `data-menu-controls`, and `aria-label`.
+   * For other elements it sets `data-menu-controls`.
+   *
+   * `data-menu-controls` is an attribute used to support arrow keys in the MenuControl class.
+   *
+   * @param {HTMLElement[]} elements - An array of HTML elements to which ARIA controls will be attached.
+   */
+  function attachControls(elements) {
+    elements.forEach(function (element) {
+      const id = element.getAttribute('data-plugin-id');
+      const submenu = element.nextElementSibling;
+
+      if (element.tagName.toLowerCase() === 'button') {
+        element.setAttribute('aria-haspopup', 'true');
+        if (submenu) {
+          const submenuId = `panel-${id}`;
+          submenu.setAttribute('id', submenuId);
+          element.setAttribute('aria-controls', submenuId);
+          element.setAttribute('data-menu-controls', submenuId);
+          element.setAttribute('aria-label', element.textContent.trim());
+        }
+      } else if (submenu) {
+        const submenuId = `panel-${id}`;
+        submenu.setAttribute('id', submenuId);
+        element.setAttribute('data-menu-controls', submenuId);
+      }
+    });
+  }
+
   /*------------------------------------*\
-    - 01 - Drupal Aria Controls
-    Attach aria controls to menu items
+    - 01 - Drupal Aria & Data Controls
+    Attach aria and data controls to menu items
   \*------------------------------------*/
   Drupal.behaviors.ariaControls = {
     attach: function (context) {
@@ -9,19 +44,12 @@
         // Find top level menu buttons
         const buttons = menu.querySelectorAll(':scope button.menu__link');
 
-        // Add aria controls for buttons & related submenus
-        buttons.forEach(function (button) {
-          const id = button.getAttribute('data-plugin-id');
-          button.setAttribute('aria-haspopup', 'true');
+        // Find menu spans for megamenu items
+        const spans = menu.querySelectorAll(':scope span.menu__link');
 
-          const submenu = button.nextElementSibling;
-          if (submenu) {
-            const submenuId = `panel-${id}`;
-            submenu.setAttribute('id', submenuId);
-            button.setAttribute('aria-controls', submenuId);
-            button.setAttribute('aria-label', button.textContent.trim());
-          }
-        });
+        // Attach controls to buttons and spans
+        attachControls(buttons);
+        attachControls(spans);
       });
     },
   };