DP-36788: Set iframe_url markup in EntityViewBuildAlterGravityFormToken

Added a line to set the iframe_url markup in the field_form_url build array. This ensures the iframe_url is properly rendered when the entity view build is altered. Included minor adjustments to improve token handling logic.

docroot/modules/custom/mass_utility/src/EntityViewBuildAlterGravityFormToken.php

@@ -55,6 +55,7 @@ public function alter(array &$build, EntityInterface $entity, EntityViewDisplayI
         return;
       }
 
+      $build["field_form_url"]["iframe_url"]['#markup'] = $iframe_url->toString();
       $gf_token = $this->requestStack->getCurrentRequest()->get('gf_token');
       if (empty($gf_token)) {
         return;