comments: fix incorrect comment links in mentions.

Fix mentions incorrectly linking to comments like this:

    https://danbooru.donmai.us/posts/1234#comment-5678

when it should have been this

    https://danbooru.donmai.us/posts/1234#comment_5678

Change comment links to this to ensure they're permanent:

    https://danbooru.donmai.us/comments/5678

The comment show action will redirect from there to the post with the
comment in context.

app/components/comment_component/comment_component.html.erb

@@ -25,7 +25,7 @@
         <% end %>
       <% end %>
     </div>
-    <%= link_to time_ago_in_words_tagged(comment.created_at), post_path(comment.post, anchor: "comment_#{comment.id}"), class: "message-timestamp" %>
+    <%= link_to time_ago_in_words_tagged(comment.created_at), comment, class: "message-timestamp" %>
   </div>
 
   <div class="content">