Add ability to hide next/prev link if on last/first page respectively

When on the last page the next link is grayed out and on the first page the previous link is grayed out. There is no way to hide the links in this case through the interface and there is no class provided for first/last to hide through css.

This can especially be an issue if you are using token replacement added in https://www.drupal.org/node/2870793. If you were to use [node:title] in the link, on the last page the next link would show the title of the current page, but grayed out, which is confusing.

I was able to solve this for my case in the entity-pager.html.twig by checking the type of link {% if link['#type'] == 'link' %}. But this would also hide the page count if a user was using this.