Add cookie banner text, page, and footer links

> Let’s start the footer links with the cookie page.
> Banner to say: "GOV.UK Notify uses cookies to make the site simpler. Find out
> more about cookies"
> Standard style one... see
> https://www.registertovote.service.gov.uk/register-to-vote/cookies or
> https://www.digitalmarketplace.service.gov.uk/cookies
>
> Let's link to the feedback form too...
> https://docs.google.com/forms/d/1AL8U-xJX_HAFEiQiJszGQw0PcEaEUnYATSntEghNDGo/viewform
> Call it Support and feedback

https://www.pivotaltracker.com/story/show/115483375

app/templates/admin_template.html

@@ -24,6 +24,10 @@
 {% endblock %}
 
 {% block cookie_message %}
+  <p>
+    GOV.UK Notify uses cookies to make the site simpler.
+    <a href="{{ url_for("main.cookies") }}">Find out more about cookies</a>
+  </p>
 {% endblock %}
 
 {% block inside_header %}
@@ -68,6 +72,14 @@
   </div>
 {% endblock %}
 
+{% block footer_support_links %}
+  <nav class="footer-nav">
+    <a href="https://docs.google.com/forms/d/1AL8U-xJX_HAFEiQiJszGQw0PcEaEUnYATSntEghNDGo/viewform">Support and feedback</a>
+    <a href="{{ url_for("main.cookies") }}">Cookies</a>
+    Built by the <a href="https://www.gov.uk/government/organisations/government-digital-service">Government Digital Service</a>
+  </nav>
+{% endblock %}
+
 {% block body_end %}
   <script type="text/javascript" src="{{ asset_url('javascripts/all.js') }}" /></script>
 {% endblock %}