use the datasources field for the nova dataplane service def

This change ports the nova OpenstackDataplaneService to use
the recently added datasources field.

This allows the default dataplane service to optionally support
constom service config via a config called nova-extra-config

This name was choosen to aling to the default custom service
config used in the ci framework.

Related: OSPRH-6407

config/services/dataplane_v1beta1_openstackdataplaneservice_nova.yaml

@@ -3,12 +3,14 @@ kind: OpenStackDataPlaneService
 metadata:
   name: nova
 spec:
-  secrets:
-    - nova-cell1-compute-config
-    # NOTE: this Secret needs to be created before deploying the data plane.
-    # It should contain an ssh key-pair in the secret fields: ssh-privatekey
-    # and ssh-publickey
-    - nova-migration-ssh-key
+  dataSources:
+    - secretRef:
+        name: nova-cell1-compute-config
+    - secretRef:
+        name: nova-migration-ssh-key
+    - configMapRef:
+        name: nova-extra-config
+        optional: true
   playbook: osp.edpm.nova
   caCerts: combined-ca-bundle
   containerImageFields: