Add a tour screen once a broadcast is approved

For a training broadcast the user doesn’t get that immediate feedback
that something has happened, like they would with a real alert, or even
sending themselves a text message.

This commit adds another tour-style page which will interrupt their
journey and hopefully reinforce the message we’ve given them earlier in
the tour.

We’re adding this because we’ve found in research that users don’t have
a good grasp of the consequences and severity of emergency alerts,
versus regular text messages.

app/main/views/broadcast.py

@@ -23,7 +23,7 @@ from app.utils import service_has_permission, user_has_permissions
 @user_has_permissions()
 @service_has_permission('broadcast')
 def broadcast_tour(service_id, step_index):
-    if step_index not in (1, 2, 3, 4, 5):
+    if step_index not in (1, 2, 3, 4, 5, 6):
         abort(404)
     return render_template(
         f'views/broadcast/tour/{step_index}.html'
@@ -275,6 +275,13 @@ def approve_broadcast_message(service_id, broadcast_message_id):
 
     broadcast_message.approve_broadcast()
 
+    if current_service.trial_mode:
+        return redirect(url_for(
+            '.broadcast_tour',
+            service_id=current_service.id,
+            step_index=6,
+        ))
+
     return redirect(url_for(
         '.view_broadcast_message',
         service_id=current_service.id,