Fix missing recipients on notification page

For some reason:
- notifications sent from CSV files have the recipient as part of the
  personalisation
- notifications sent via the API don’t have the recipient as part of the
  personalisation

I’d only tested it locally with CSV-sent files so didn’t spot this. The
`conftest.py` fixtures we set up like the API already, but we didn’t
have an explicit test.

This commit adds a method to append the recipient to the
personalisation, so we can populate the template with it.

tests/app/main/views/test_notifications.py

@@ -43,6 +43,9 @@ def test_notification_status_page_shows_details(
         notification_id=fake_uuid
     )
 
+    assert normalize_spaces(page.select('.sms-message-recipient')[0].text) == (
+        'To: 07123456789'
+    )
     assert normalize_spaces(page.select('.sms-message-wrapper')[0].text) == (
         'service one: hello Jo'
     )