Add check tour notification page

On submit of form on this page, will continue to normal sending flow
which can be shared code as there is no longer previous context needed
of where they have come from

app/main/views/tour.py

@@ -111,4 +111,30 @@ def _get_tour_step_back_link(service_id, template_id, step_index):
 @main.route("/services/<uuid:service_id>/tour/<uuid:template_id>/check", methods=['GET'])
 @user_has_permissions('send_messages', restrict_admin_usage=True)
 def check_tour_notification(service_id, template_id):
-    pass
+    db_template = current_service.get_template(template_id)
+
+    template = get_template(
+        db_template,
+        current_service,
+        show_recipient=True,
+    )
+
+    placeholders = fields_to_fill_in(template, prefill_current_user=True)
+
+    if not all_placeholders_in_session(template.placeholders):
+        return redirect(url_for(
+            '.tour_step', service_id=current_service.id, template_id=template_id, step_index=1
+        ))
+
+    back_link = url_for(
+        '.tour_step', service_id=current_service.id, template_id=template_id, step_index=len(placeholders)
+    )
+
+    template.values = get_recipient_and_placeholders_from_session(template.template_type)
+
+    return render_template(
+        'views/notifications/check.html',
+        template=template,
+        back_link=back_link,
+        help='2',
+    )