When someone complains about an email from the platform we get a callback from SES.

A new platform admin page Email complaints has been added to surface those complaints.
Eventually the complaints will be visible to the services so they can remove the email address from their mailing list.

Next thing to implement is "x email complaints" warning on the platform admin summary page.

app/templates/views/platform-admin/_base_template.html

@@ -19,7 +19,8 @@
           ('Providers', url_for('main.view_providers')),
           ('Email branding', url_for('main.email_branding')),
           ('Letter jobs', url_for('main.letter_jobs')),
-          ('Inbound SMS numbers', url_for('main.inbound_sms_admin'))
+          ('Inbound SMS numbers', url_for('main.inbound_sms_admin')),
+          ('Email Complaints', url_for('main.platform_admin_list_complaints'))
         ] %}
           <li>
             <a href="{{ url }}">