[1h] Creating order with empty title is allowed

Click on Add item button on 'Add order' page, add items, click 'Save' leads to saving order with empty name.
Expected: warning of impossibility to save order without name.

Look at the 'Add order' page component and the save handler. The issue is that validation for the order title is missing. Find where the order data is submitted and add a check for an empty title, showing a warning. Test by trying to save an order without a name.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.