remove PM resource interaction from StartGamePacket

also lose the cache, because it's not very useful ...

src/data/bedrock/LegacyItemIdToStringIdMap.php

@@ -0,0 +1,40 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\data\bedrock;
+
+use pocketmine\utils\AssumptionFailedError;
+use pocketmine\utils\SingletonTrait;
+use function file_get_contents;
+use function is_array;
+use function is_int;
+use function is_string;
+use function json_decode;
+
+final class LegacyItemIdToStringIdMap extends LegacyToStringBidirectionalIdMap{
+	use SingletonTrait;
+
+	public function __construct(){
+		parent::__construct(\pocketmine\RESOURCE_PATH . 'vanilla/item_id_map.json');
+	}
+}