[Admin/Backend] Support custom price of goods in POS page

[somnisomni]

Use Cases : When if the booth owner offers a/some goods as free or different price sometimes to customer

Backend

• Accept customPrice: number property for each goods item in goods order create DTO
• When creating a goods order history, use this property as price if provided, otherwise use default price of the goods

Frontend

• Make setting custom price for goods in order list available
  • On list item click -> Show dialog for editing price and count(#2)
• If custom price is set for the goods, display the custom price instead of default price (Add highlight(icon or text color) for better visibility)
• Include customPrice: number property when call API