enable CORS for Gnocchi and Keystone for grafana datasource

adding cors section to keystone and gnocchi templates when
grafana is enabled

Change-Id: I54f4c06ed64254df0f9481e461c9393a399212a3
Closes-bug: #1651796

ansible/roles/gnocchi/templates/gnocchi.conf.j2

@@ -55,3 +55,8 @@ ceph_username = gnocchi
 ceph_keyring = /etc/ceph/ceph.client.gnocchi.keyring
 ceph_conffile = /etc/ceph/ceph.conf
 {% endif %}
+
+{% if enable_grafana | bool %}
+[cors]
+allowed_origin = {{ public_protocol }}://{{ kolla_external_fqdn }}:{{ grafana_server_port }}
+{% endif %}

ansible/roles/keystone/templates/keystone.conf.j2

@@ -53,3 +53,8 @@ hmac_keys = {{ osprofiler_secret }}
 connection_string = elasticsearch://{{ elasticsearch_address }}:{{ elasticsearch_port }}
 {% endif %}
 {% endif %}
+
+{% if enable_grafana | bool %}
+[cors]
+allowed_origin = {{ public_protocol }}://{{ kolla_external_fqdn }}:{{ grafana_server_port }}
+{% endif %}