Accept draft orders with line item props (#12)

- Draft orders with line item props or note attributes were being
refused with error note_attributes:expected Hash to be a Array
- It seems the draft order API expects line item properties and note attributes
to be wrapped in an array:
https://help.shopify.com/api/reference/draftorder#note-attributes-property

src/Services/DraftOrder.php

@@ -120,7 +120,11 @@ public function createDraftOrderFromCart(CartModel $cart)
 
         $draftOrderModel->setLineItems($draftOrderLineItems);
         $draftOrderModel->setNote($cart->getNote());
-        $draftOrderModel->setNoteAttributes($cart->getAttributes());
+
+        $cartAttributes = $cart->getAttributes();
+        if (!empty($cartAttributes)) {
+            $draftOrderModel->setNoteAttributes([$cartAttributes]);
+        }
 
         return $draftOrderModel;
     }

src/Services/DraftOrderLineItem.php

@@ -96,6 +96,11 @@ public function createDraftOrderLineItemFromCartItem(CartItem $cartItem)
             }
         }
 
+        $lineItemProperties = $draftOrderLineItem->getProperties();
+        if (!empty($lineItemProperties)) {
+            $draftOrderLineItem->setProperties([$lineItemProperties]);
+        }
+
         return $draftOrderLineItem;
     }