The "add link" operation in the Menu List should check Menu Link Content create access.

Problem/Motivation

This isn't an issue if only core is in use, but if contrib/custom change these permissions (which does happen!), this can result in operations linking to unavailable forms.

Currently MenuListBuilder provides the "Add Link" operation if the menu edit operation is present.

 if (isset($operations['edit'])) {
      $operations['edit']['title'] = t('Edit menu');
      $operations['add'] = [
        'title' => t('Add link'),
        'weight' => 20,
        'url' => $entity->toUrl('add-link-form'),
        'query' => [
          'destination' => $entity->toUrl('edit-form')->toString(),
        ],
      ];
    }

However, these are two distinct entity types that could have their own access restrictions.
Instead of isset($operations['edit']), it would be more accurate to check ->createAccess() on the access control handler for menu link content.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet