Issue #3307481 by Berdir: Change library item canonical access to use the...

      // Display library items using default theme.

      $canonical_route->setOption('_admin_route', FALSE);

      // Restrict access based on permission.

      $canonical_route->addRequirements([

        '_permission' => 'administer paragraphs library+create paragraph library item+edit paragraph library item',

      ]);

      // Restrict access to users who are allowed to update the entity.

      $canonical_route->setRequirement('_entity_access', "{$entity_type->id()}.update");

    }

    return $route_collection;

  }