Fix accessor addition logic in ChestShop

This commit refactors the addAccessor command logic in the ChestShop application. It now compares the newAccessor to the actual owner of the chest shop instead of the player's ID. This change ensures more accurate assignment of access permissions.

src/main/java/com/Acrobot/ChestShop/Commands/AddAccessor.java

@@ -61,7 +61,8 @@ public boolean onCommand(CommandSender sender, Command command, String label, St
             return true;
         }
 
-        if (player.getUniqueId().equals(newAccessor)) {
+        UUID owner = ChestShopSign.getOwner(sign);
+        if (owner.equals(newAccessor)) {
             sender.sendMessage(Messages.prefix(Messages.OWNER_CANT_BE_ACCESSOR));
             return true;
         }