Check text message sender before going live

We often check that a service has an appropriate text message sender as
a condition of them going live. We don’t mention this anywhere.

The services for whom GOVUK is definitely not an appropriate sender are
those in local government. As we have more of these teams starting to
use Notify, we should streamline the process by making this check
automated.

This commit adds that check, for teams who:
- have text message templates
- have self-declared as NHS or local government

app/templates/views/service-settings/request-to-go-live.html

@@ -38,6 +38,12 @@
             )|safe,
           ) }}
         {% endif %}
+        {% if has_sms_templates and shouldnt_use_govuk_as_sms_sender %}
+          {{ task_list_item(
+            not sms_sender_is_govuk,
+            'Change your text message sender from GOVUK'
+          ) }}
+        {% endif %}
       {% endcall %}
       <p>
         You also need to accept our <a href="{{ url_for('.terms') }}">terms of use</a>.