Update feature tests when checking for page titles

As we are now using the heading component from the gem, page titles have the `gem-c-heading__text` class

spec/features/content_store_organisations_spec.rb

@@ -15,7 +15,7 @@
   end
 
   scenario "renders page title" do
-    expect(page.has_css?(".gem-c-title__text", text: organisations_content_hash[:title])).to be(true)
+    expect(page.has_css?(".gem-c-heading__text", text: organisations_content_hash[:title])).to be(true)
   end
 
   scenario "has autodiscovery links to the API" do

spec/features/ministers_spec.rb

@@ -11,7 +11,7 @@
     end
 
     scenario "renders page title" do
-      expect(page).to have_selector(".gem-c-title__text", text: I18n.t("ministers.title"))
+      expect(page).to have_selector(".gem-c-heading__text", text: I18n.t("ministers.title"))
     end
 
     scenario "renders the lead paragraph with anchor links" do

spec/features/step_nav_page_spec.rb

@@ -13,8 +13,7 @@
   end
 
   it "renders the title" do
-    expect(page).to have_selector(".gem-c-title")
-    expect(page).to have_selector(".gem-c-title__text", text: "Learn to drive a car: step by step")
+    expect(page).to have_selector(".gem-c-heading__text", text: "Learn to drive a car: step by step")
   end
 
   it "renders the step by step navigation component" do

spec/features/world_index_spec.rb

@@ -17,7 +17,7 @@
     end
 
     scenario "renders the page title" do
-      expect(page).to have_selector(".gem-c-title__text", text: "Help and services around the world")
+      expect(page).to have_selector(".gem-c-heading__text", text: "Help and services around the world")
     end
 
     scenario "renders a link to all foreign office posts" do

spec/support/courts_pages_helper.rb

@@ -39,7 +39,7 @@ def the_correct_title
 
   def the_courts_title
     expect(page).to have_title("#{@title} - GOV.UK")
-    expect(page).to have_selector(".gem-c-title__text", text: @title)
+    expect(page).to have_selector(".gem-c-heading__text", text: @title)
   end
 
   def and_featured_links