fix: add missing search method to relation controllers

Author: alexzarbn

src/Concerns/HandlesRelationStandardOperations.php

@@ -210,6 +210,18 @@ protected function afterIndex(Request $request, Model $parentEntity, $entities)
         return null;
     }
 
+    /**
+     * Filters, sorts, and fetches the list of resources.
+     *
+     * @param Request $request
+     * @param $parentKey
+     * @return CollectionResource
+     */
+    public function search(Request $request, $parentKey)
+    {
+        return $this->index($request, $parentKey);
+    }
+
     /**
      * Create new relation resource.
      *