Enable nested virtualization by default

* Add configure kernel parameter `kvm-intel nested=y`
* Configure nova to use kvm host-passthrough libvirt driver.

Change-Id: I8e3b6c6adedb4db481981e2ce4f4721b9f30f511

global/baremetal/bootactions/nested-virt.yaml

@@ -0,0 +1,23 @@
+---
+schema: 'drydock/BootAction/v1'
+metadata:
+  schema: 'metadata/Document/v1'
+  name: nested-virt
+  labels:
+    name: nested-virt-global
+    application: 'drydock'
+  layeringDefinition:
+    abstract: false
+    layer: global
+  storagePolicy: 'cleartext'
+data:
+  signaling: false
+  assets:
+    - path: /etc/modprobe.d/nested-virt.conf
+      type: file
+      permissions: '644'
+      data_pipeline:
+        - utf8_decode
+      data: |
+        options kvm-intel nested=y
+...

global/software/charts/osh/openstack-compute-kit/nova.yaml

@@ -337,6 +337,10 @@ data:
       configmap: tenant-ceph-etc
       user_secret_name: pvc-tceph-client-key
     conf:
+      nova:
+        libvirt:
+          cpu_mode: 'host-passthrough'
+          virt_type: kvm
       logging:
         loggers:
           keys: