Refactor callback functions to arrow functions

The callback functions used in the addViewTransformer method in FilterType.php and AggregatorType.php were replaced with shorter arrow functions. This change was made to increase code readability and encourage consistency throughout the codebase.

src/Bundle/ChillReportBundle/Tests/DependencyInjection/ChillReportExtensionTest.php

@@ -41,7 +41,7 @@ final class ChillReportExtensionTest extends KernelTestCase
         }
 
         if (!$reportFounded) {
-            throw new \Exception('Class Chill\\ReportBundle\\Entity\\Report not found in chill_custom_fields.customizables_entities', 1);
+            throw new \Exception('Class Chill\ReportBundle\Entity\Report not found in chill_custom_fields.customizables_entities', 1);
         }
     }
 }