Add to cart feature integration using Redux

[shivang1305]

• Use redux to add any item from menu page to cart
• The restaurant menu page should hold the state of the item after adding it to the cart.
• The cart should be tied to the specific restaurant.
• User is able to add any number of items and it should be shown in the UI.

[shivang1305]

• Cart is integrated with a single restaurant at a time.
• User can add any number of items from a single restaurant only.
• Cart items will be replaced with a popup when user tries to add items from a different restaurant.

[shivang1305]

• Cart is now able to capture the quantity of the item.
• If user adds the same item it increases the quantity instead of adding the same item again to the card like it was doing earlier.
• If user removes a specific item from the cart it decreases its quantity if (quantity > 1) and removes the item if (quantity == 1)

[shivang1305]

This issue is resolved.