Show permalinked trashed comments to moderators

Currently, when viewing the permalink for a trashed comment, the comment will be empty. To make it easier for forum moderators to see threads with trashed comments, this change will show the trashed comment within a nested thread when the permalink of the comment is viewed. In addition, the poster of a trashed comment will be able to view the permalink. This is achieved through editing the template _layouts/comment.html.twig.