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">

app/models/comment.rb

@@ -21,7 +21,7 @@ class Comment < ApplicationRecord
   mentionable(
     :message_field => :body,
     :title => ->(user_name) {"#{creator.name} mentioned you in a comment on post ##{post_id}"},
-    :body => ->(user_name) {"@#{creator.name} mentioned you in a \"comment\":#{Routes.post_path(post, anchor: "comment-#{id}")} on post ##{post_id}:\n\n[quote]\n#{DText.extract_mention(body, "@" + user_name)}\n[/quote]\n"}
+    :body => ->(user_name) {"@#{creator.name} mentioned you in comment ##{id} on post ##{post_id}:\n\n[quote]\n#{DText.extract_mention(body, "@" + user_name)}\n[/quote]\n"}
   )
 
   module SearchMethods

test/unit/comment_test.rb

@@ -71,7 +71,7 @@ class CommentTest < ActiveSupport::TestCase
 
           dmail = Dmail.last
           assert_equal(<<-EOS.strip_heredoc, dmail.body)
-            @#{@comment.creator.name} mentioned you in a \"comment\":/posts/#{@comment.post_id}#comment-#{@comment.id} on post ##{@comment.post_id}:
+            @#{@comment.creator.name} mentioned you in comment ##{@comment.id} on post ##{@comment.post_id}:
 
             [quote]
             Hey @#{@user2.name} check this out!