Item-from-string parsing no longer depends on ItemIds

after this is done I'm banning the constant() function.

tests/phpunit/item/LegacyStringToItemParserTest.php

@@ -0,0 +1,58 @@
+<?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\item;
+
+use PHPUnit\Framework\TestCase;
+
+class LegacyStringToItemParserTest extends TestCase{
+
+	/**
+	 * @return mixed[][]
+	 * @phpstan-return list<array{string,int,int}>
+	 */
+	public function itemFromStringProvider() : array{
+		return [
+			["dye:4", ItemIds::DYE, 4],
+			["351", ItemIds::DYE, 0],
+			["351:4", ItemIds::DYE, 4],
+			["stone:3", ItemIds::STONE, 3],
+			["minecraft:string", ItemIds::STRING, 0],
+			["diamond_pickaxe", ItemIds::DIAMOND_PICKAXE, 0],
+			["diamond_pickaxe:5", ItemIds::DIAMOND_PICKAXE, 5]
+		];
+	}
+
+	/**
+	 * @dataProvider itemFromStringProvider
+	 * @param string $string
+	 * @param int    $id
+	 * @param int    $meta
+	 */
+	public function testFromStringSingle(string $string, int $id, int $meta) : void{
+		$item = LegacyStringToItemParser::getInstance()->parse($string);
+
+		self::assertEquals($id, $item->getId());
+		self::assertEquals($meta, $item->getMeta());
+	}
+}