Support for instagram post with multiple images

Hello;

I found the same issue and tracked it down to the following code:

    foreach ($posts as $post) {
      $items[] = [
        '#theme' => 'socialfeed_instagram_post_' . $post['raw']->type,
        '#post' => $post,
        (...)
      ];
    }

The type of post is set to "carousel" but there is no "socialfeed_instagram_post_carousel" template declared, only "image" and "video". The solution is to add the template. I attached a patch that solves the problem.

I tried this on my install and it works. For the template, a copy of socialfeed_instagram_post_image works as a charm. Still, I think is good to have a separate template: this way, people can style carousel thumbnails different from image thumbnails if they need to (i.e, add an icon indicating that there are more images that can be seen on Instagram, etc...)

Sorry, i forgot to update the template preprocess function in order to make links work on carousel thumbnails.

This patch is the good one, forget the patch on #3.