Enable keystone cadf notifications

It will allow to configure keystone event notifications
using CADF, as documented on:
https://docs.openstack.org/developer/keystone/event_notifications.html

CADF events provide auditing capabilities for compliance with
security.

Change-Id: Id16b264c295b9e3adbf960366ff8328ba8dcd485

capabilities-map.yaml

@@ -582,3 +582,8 @@ topics:
             description:
             requires:
               - overcloud-resource-registry-puppet.yaml
+      - title: Keystone CADF auditing
+        description: Enable CADF notifications in Keystone for auditing
+        environments:
+          - file: environments/cadf.yaml
+            title: Keystone CADF auditing

environments/cadf.yaml

@@ -0,0 +1,2 @@
+parameter_defaults:
+  KeystoneNotificationFormat: cadf