Properly identify products in the wishlist(s)

Hi CIF Team.

Opened as a feature request, but could also be treated as a bug, as the functionalities described in this issue are very basic and the end user could expect to be there. The current functionality could cause confusions.

### User Story
As a registered user, I want to identify my favorite products easily, so I can access and purchase them quickly.

### Description & Motivation
When a product is in a wishlist(s), the product should be identified properly when it’s rendered. That means that the addToWishList button, when enabled, should be marked someway (a CSS class).
This should work on the initial page load, but also when the user adds a product to the wishlist (after the addToWishlist event), and after adding products to the list (the ‘Load More’ button, in the Search Results, when enabled).
As a reference, the venia.magento.com site has already implemented this.

### Deliverables
This affects the Product Carousel, the Product Details, and the Search Results components (at least).

### Acceptance Criteria
All rendered products should be marked as a wishlist products, if they are in a wishlist(s).

- In the initial page load, the product is marked as favorite, in product carousel
- In the initial page load, the product is marked as favorite, in product details page
- In the initial page load, the product is marked as favorite, in product results page
- After addToWishlist event, the product is marked as favorite, in product carousel
- After addToWishlist event, the product is marked as favorite, in product details page
- After addToWishlist event, the product is marked as favorite, in product results page
- After adding products to the list (load more button), the product is marked as favorite, in product results page

Start by inspecting the Product Carousel, Product Details, and Search Results component entry points, focusing on the addToWishlist event and the Search Results Load More flow. Check how rendered products and the addToWishList button are marked, then verify the acceptance criteria for initial loads, wishlist additions, and newly loaded products.

Written by the indexing model from the issue text.