Make potion types dynamic

It became obvious this was needed when I wanted to make new IDs for existing items - there's no way I'm unrolling those registrations...

src/item/SplashPotion.php

@@ -23,6 +23,7 @@ declare(strict_types=1);
 
 namespace pocketmine\item;
 
+use pocketmine\data\bedrock\PotionTypeIdMap;
 use pocketmine\entity\Location;
 use pocketmine\entity\projectile\SplashPotion as SplashPotionEntity;
 use pocketmine\entity\projectile\Throwable;
@@ -32,13 +33,25 @@ class SplashPotion extends ProjectileItem{
 
 	private PotionType $potionType;
 
-	public function __construct(ItemIdentifier $identifier, string $name, PotionType $potionType){
+	public function __construct(ItemIdentifier $identifier, string $name){
+		$this->potionType = PotionType::WATER();
 		parent::__construct($identifier, $name);
-		$this->potionType = $potionType;
+	}
+
+	public function getMeta() : int{
+		return PotionTypeIdMap::getInstance()->toId($this->potionType);
 	}
 
 	public function getType() : PotionType{ return $this->potionType; }
 
+	/**
+	 * @return $this
+	 */
+	public function setType(PotionType $type) : self{
+		$this->potionType = $type;
+		return $this;
+	}
+
 	public function getMaxStackSize() : int{
 		return 1;
 	}