Create states for payment

[axentioialexandru95]

We need a successful and a failed screen page for payments redirects.

AC

• [x] Create a successful payment page with info "Your payment has been received, we will be notifying you soon."
• [x] Create a failed payment page
• [x] When no items are added to the cart, show a message that the cart is empty and show a link to go back to shop
• [x] Add cart to navbar when mobile, not on secondary nav