Add link to download summary in XLSX format again

It was removed in commit 128a8164 alongside everything related to the
legislation process summary.

Co-Authored-By: taitus <sebastia.roig@gmail.com>

spec/controllers/legislation/processes_controller_spec.rb

@@ -0,0 +1,13 @@
+require "rails_helper"
+
+describe Legislation::ProcessesController do
+  let(:legislation_process) { create(:legislation_process, end_date: Date.current - 1.day) }
+
+  it "download excel file test" do
+    create(:legislation_question, process: legislation_process, title: "Question 1")
+
+    get :summary, params: { id: legislation_process, format: :xlsx }
+
+    expect(response).to be_success
+  end
+end