Loosen restrictions on inventory sizing

Allows creating (but not opening) inventories created eg via Bukkit.createInventory(..., InventoryType.PLAYER);

By: md_5 <git@md-5.net>

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftHumanEntity.java

@@ -333,7 +333,7 @@ public class CraftHumanEntity extends CraftLivingEntity implements HumanEntity {
                         customSize = Containers.GENERIC_9X6;
                         break;
                     default:
-                        throw new IllegalArgumentException("Unsupported custom size " + inventory.getSize());
+                        throw new IllegalArgumentException("Unsupported custom inventory size " + inventory.getSize());
                 }
                 openCustomInventory(inventory, player, customSize);
                 break;