Add FASP follow recommendation support (#34964)

spec/requests/api/v2/suggestions_spec.rb

@@ -34,5 +34,14 @@ RSpec.describe 'Suggestions API' do
         end
       )
     end
+
+    context 'when `follow_recommendation` FASP is enabled', feature: :fasp do
+      it 'enqueues a retrieval job and adds a header to inform the client' do
+        get '/api/v2/suggestions', headers: headers
+
+        expect(Fasp::FollowRecommendationWorker).to have_enqueued_sidekiq_job
+        expect(response.headers['Mastodon-Async-Refresh']).to be_present
+      end
+    end
   end
 end