Product duplicates in wishlist after user login

[ankhy-dev]

After init hook, assign_to_user method converted all session’s wishlists to user wishlists, but if user had products in wishlist before (add to wishlist product X → logout → add to wishlist product X → login), then user got product duplicates in yith_wcwl table. Because this function adds user_id to records in the table without checking if the current product already assigned to user

Case:
If you already have a product in the wishlist (as registered user) and add the same product as a guest(user not logged in), then after login you will have 2 records of the same product in the database, and you need to click twice the “remove product from the wishlist” button