tools/generate-bedrock-data-from-packets: generate less noise for items

if we have only a name (the majority case), we can just return the name directly instead of an object.
this massively reduces the amount of noise in the files as seen in pmmp/BedrockData@f814036229

src/crafting/CraftingManagerFromDataHelper.php

@@ -162,7 +162,7 @@ final class CraftingManagerFromDataHelper{
 		}
 
 		$mapper = new \JsonMapper();
-		$mapper->bStrictObjectTypeChecking = true;
+		$mapper->bStrictObjectTypeChecking = false; //to allow hydrating ItemStackData - since this is only used for offline data it's safe
 		$mapper->bExceptionOnUndefinedProperty = true;
 		$mapper->bExceptionOnMissingData = true;