Simplify the way the embed view is created (#1590)

* Add coverage for embedded status view

* Refactor embed view to eliminate @external_links variable

spec/controllers/stream_entries_controller_spec.rb

@@ -17,4 +17,14 @@ RSpec.describe StreamEntriesController, type: :controller do
       expect(response).to have_http_status(:success)
     end
   end
+
+  describe 'GET #embed' do
+    it 'returns embedded view of status' do
+      get :embed, params: { account_username: alice.username, id: status.stream_entry.id }
+
+      expect(response).to have_http_status(:success)
+      expect(response.headers['X-Frame-Options']).to eq 'ALLOWALL'
+      expect(response).to render_template(layout: 'embedded')
+    end
+  end
 end