Add api for set emoji reactions to toot

app/serializers/rest/emoji_reactions_grouped_by_name_serializer.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class REST::EmojiReactionsGroupedByNameSerializer < ActiveModel::Serializer
+  include RoutingHelper
+
   attributes :name, :count
 
   attribute :me, if: :current_user?
@@ -14,10 +16,22 @@ class REST::EmojiReactionsGroupedByNameSerializer < ActiveModel::Serializer
   end
 
   def custom_emoji?
-    object.respond_to?(:custom_emoji)
+    object.custom_emoji.present?
   end
 
   def account_ids?
     object.respond_to?(:account_ids)
   end
+
+  def url
+    full_asset_url(object.custom_emoji.image.url)
+  end
+
+  def static_url
+    full_asset_url(object.custom_emoji.image.url(:static))
+  end
+
+  def domain
+    object.custom_emoji.domain
+  end
 end