Add extra letter spacing to phone number search

This is another place where you might be transcribing a phone number and
having it spaced out will make it easier for you to spot errors.

app/templates/views/notifications.html

@@ -25,7 +25,7 @@
       action="{{ url_for('.view_notifications', service_id=current_service.id, message_type=message_type) }}"
       class="grid-row"
     >
-      <div class="column-three-quarters">
+      <div class="column-three-quarters {% if message_type == 'sms' %}extra-tracking{% endif %}">
         {{ textbox(
           search_form.to,
           width='1-1',