Add functionality in the product listing pages

[techy4shri]

Currently, a user can only select an item onc in the product list. They have to go to the cart page if they want to increase the number of items. The filter, after addign dummyjson API, does not work. All the products are not listed despite the API having a huge list of products. I can incorporate these changes and ensure overall proper functionality. Kindly assign me this issue under GSSOC'24 .