Add to cart function

[barbigrade]

Value Proposition

As a customer I need to be able to add the items I want to buy to my shopping basket to be able to purchase them at a later stage

Description

Acceptance Criteria

• [x] The shopping cart should be accessible from all pages through an icon in the header
• [x] The "add to basket" button adds any selected item to the shopping cart page on click
• [x] If the cart is empty, display the default (your basket is empty) shopping cart page

Tasks

• [x] Include the shopping basket icon in the header and link to the shopping cart page
• [x] Write add-to-cart logic for the existing product component using useState and product id
• [x] Update the shopping cart page and add an if/else statement for the empty cart display