ヘルプを Wiki から分離 (#424) (#430)

画面上でのテストは完了．
移行にす早さが求められるので，準備ができたらマージする．

Reviewed-on: #430
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/app/representations/wiki_page_repr.rb

@@ -13,6 +13,7 @@ module WikiPageRepr
   def tag_description description
     tag = description.tag
     { 'id' => description.id,
+      'resource_type' => 'tag_description',
       'tag_name_id' => tag.tag_name('ja')&.id,
       'body' => description.body,
       'created_user_id' => description.created_by_user_id,
@@ -26,7 +27,7 @@ module WikiPageRepr
   end
 
   def tag_group tag_group
-    TagGroupRepr.tag_group(tag_group)
+    TagGroupRepr.tag_group(tag_group).merge('resource_type' => 'tag_group')
   end
 
   def many wiki_pages