Reorganise templates for API keys page

This adds another layer of folder structure to the templates to match
the new URLs, which have another layer of hierarchy.

app/templates/views/api/keys/create.html

@@ -0,0 +1,22 @@
+{% extends "withnav_template.html" %}
+{% from "components/page-footer.html" import page_footer %}
+{% from "components/textbox.html" import textbox %}
+{% from "components/radios.html" import radios %}
+
+{% block page_title %}
+  Add a new API key – GOV.UK Notify
+{% endblock %}
+
+{% block maincolumn_content %}
+
+  <h1 class="heading-large">
+    Create an API key
+  </h1>
+
+  <form method="post">
+    {{ radios(form.key_type) }}
+    {{ textbox(form.key_name, label='Name for this key') }}
+    {{ page_footer('Continue') }}
+  </form>
+
+{% endblock %}

app/templates/views/api/keys/revoke.html

@@ -0,0 +1,31 @@
+{% extends "withnav_template.html" %}
+{% from "components/page-footer.html" import page_footer %}
+{% from "components/api-key.html" import api_key %}
+
+{% block page_title %}
+  Revoke API key – GOV.UK Notify
+{% endblock %}
+
+{% block maincolumn_content %}
+
+    <h1 class="heading-large">
+      Revoke API key
+    </h1>
+
+    <p>
+      ‘{{ key_name }}’ will no longer let you connect to GOV.UK Notify.
+    </p>
+    <p>
+      You can’t undo this.
+    </p>
+
+    <form method="post">
+      {{ page_footer(
+        'Revoke this API key',
+        back_link=url_for('.api_keys', service_id=current_service.id),
+        back_link_text='Back to API keys',
+        destructive=True
+      ) }}
+    </form>
+
+{% endblock %}

app/templates/views/api/keys/show.html

@@ -0,0 +1,28 @@
+{% extends "withnav_template.html" %}
+{% from "components/page-footer.html" import page_footer %}
+{% from "components/api-key.html" import api_key %}
+
+{% block page_title %}
+  New API key – GOV.UK Notify
+{% endblock %}
+
+{% block maincolumn_content %}
+
+
+    <h1 class="heading-large">
+      New API key
+    </h1>
+
+    <p>
+      Copy your key to somewhere safe. You won’t be able to see it again
+      once you leave this page.
+    </p>
+
+    {{ api_key(secret, key_name) }}
+
+    {{ page_footer(
+      secondary_link=url_for('.api_keys', service_id=current_service.id),
+      secondary_link_text='Back to API keys'
+    ) }}
+
+{% endblock %}