Add milestone tabs deprecation view

app/views/projects/milestones/show.html.haml

@@ -78,5 +78,6 @@
     .alert.alert-success.prepend-top-default
       %span All issues for this milestone are closed. You may close this milestone now.
+  = render 'deprecation_message'
   = render 'shared/milestones/tabs', milestone: @milestone
   = render 'shared/milestones/sidebar', milestone: @milestone, project: @project, affix_offset: 153