add RBD Provisioner Addon (#3667) (#3668)

Based on the CephFS Provisioner Addon, the following changes have been made:
 - Upstream v2.1.1-k8s1.11
 - Configurable Provisioner replicas

roles/kubernetes-apps/external_provisioner/rbd_provisioner/templates/role-rbd-provisioner.yml.j2

@@ -0,0 +1,13 @@
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: rbd-provisioner
+  namespace: {{ rbd_provisioner_namespace }}
+rules:
+  - apiGroups: [""]
+    resources: ["secrets"]
+    verbs: ["get"]
+  - apiGroups: [""]
+    resources: ["endpoints"]
+    verbs: ["get", "list", "watch", "create", "update", "patch"]