Nested product/category GQL fields must use Storefront resolver.

Need to review existing GQL schema and override/introduce new resolvers for all product/category fields.

E.g. the following query use "product" which need to be overridden:

  addSimpleProductsToCart(input: {
    cart_id: "1drXoOv8VZCcH8JYUF3KCXHqJBzeV1pv",
    cart_items: [{data: {sku: "simple-2", quantity: 1}}]
  }) {
    cart {
      items {
        id
        prices{
          price {
            value
          }
        }
        quantity
        product { //This should be overridedn with Storefront resolver
          sku
          name
          image {
            label
            url
          }
        }
      }
    }
  }
}

Example of overriding
https://github.com/magento/catalog-storefront/commit/dfb66e4ac3baf99c69e42e39b1732b67c4a78421#diff-f0a25dfa8dd4f3476fe6ec0e598a377cR7-R10

Review the existing GQL schema and trace nested product and category fields, starting with the product field in the example cart query. Compare the resolver override pattern in commit dfb66e4ac3baf99c69e42e39b1732b67c4a78421. Done means all relevant product and category fields use Storefront resolvers.