Support pagination of remote emoji packs and files
We already have pagination for local emoji packs and files, so it makes sense if we also have pagination for remote packs and files inside those packs.
I would also suggest a small change regarding deleting files in a local pack. Earlier, when deleting (`DELETE api/pleroma/emoji/packs/:packName/files), the shortcode was passed in the body of the request. Now such request throws an error and the shortcode needs to be included in the URL. This breaks deletion of files with special characters in the shortcode. So I think it's better to pass a shortcode in the request's body.