Unify how --format is handle by commands

Author: fabpot

Command/DebugCommand.php

@@ -272,6 +272,7 @@ private function completeOptions(string $class, CompletionSuggestions $suggestio
         $suggestions->suggestValues($resolvedType->getOptionsResolver()->getDefinedOptions());
     }
 
+    /** @return string[] */
     private function getAvailableFormatOptions(): array
     {
         return (new DescriptorHelper())->getFormats();