Introduce CoreDNS DaemonSet

This enables coredns to run as a daemonset across the control plane
hosts, for increased resiliency.  This change retains the deployment-
controlled coredns pods as well (with two replicas) to make sure there
is no interruption to DNS service while the change is rolled out in
existing Airship deployments.  The deployment can be turned off in a
future release, once the daemonset is in place.

Change-Id: I4678ff2490ab36a2f5a1cc5030492d85ef70b7ac

global/software/charts/kubernetes/dns/coredns.yaml

@@ -141,6 +141,18 @@ data:
   chart_name: coredns-htk
   release: coredns-htk
   namespace: coredns-htk
-  values: {}
+  values:
+    pod:
+      # TODO: replicas can be removed once we switch coredns to
+      # DaemonSet-only.  It will be deployed with both DaemonSet
+      # and Deployment-managed pods as we transition to DaemonSet.
+      replicas:
+        coredns: 2
+    manifests:
+      daemonset: true
+      # TODO: `deployment` can be set to false once we switch coredns to
+      # DaemonSet-only.  It will be deployed with both DaemonSet
+      # and Deployment-managed pods as we transition to DaemonSet.
+      deployment: true
   dependencies: []
 ...

global/software/config/versions.yaml

@@ -45,7 +45,7 @@ data:
         type: git
       coredns:
         location: https://opendev.org/airship/promenade
-        reference: 44b5fae04788c6a28de0f9a2e132204561474d47
+        reference: 37140647342eecfa5d02dc38dcf0474ac32a02b7
         subpath: charts/coredns
         type: git
       coredns-htk: