Include unit selling price in order approval email notification template

Summary:

It is essential to modify the sales order notification template to add the unit price of the products, which is relevant data for approvers to evaluate the approval request for each order. All orders go through the approval flow and it is the managers and sales persons who approve these requests. They are people who are usually traveling or moving around and therefore, the easiest way to carry out this task is to use email, however, the notification does not provide the unit price which is the most important data when deciding whether to process the order or not.