PlayerBlockPickEvent: remove setResultItem()

the same behaviour can be achieved by cancelling the event and setting the held item manually. Allowing this to be changed increases the complexity of dealing with survival block picking.

src/pocketmine/event/player/PlayerBlockPickEvent.php

@@ -50,8 +50,4 @@ class PlayerBlockPickEvent extends PlayerEvent implements Cancellable{
 	public function getResultItem() : Item{
 		return $this->resultItem;
 	}
-
-	public function setResultItem(Item $item) : void{
-		$this->resultItem = clone $item;
-	}
 }