Add Coupon Code Functionality to Cart.html Page

[Shweta-1902]

The Cart.html page currently lacks a section for users to enter a coupon code and adjust the total cost accordingly. I would like to implement this feature, allowing users to input a coupon and have the total cost dynamically updated based on the discount applied.

Please assign this issue to me under the labels of GSSoC Ext and Hacktoberfest.

Thank you!

[github-actions[bot]]

Hi there! Thanks for opening this issue @Shweta-1902!. We appreciate your contribution to this open-source project. We aim to respond or assign your issue as soon as possible.

[Anjaliavv51]

@Shweta-1902 go ahead.