Implement NodeStage and NodeUnstage for rbd

in NodeStage RPC call  we  have to map the
device to the node plugin and make  sure  the
the device will be mounted to  the global path

in  nodeUnstage request unmount the device from
global path and unmap the device

if the volume mode is block  we will be creating
a file inside a stageTargetPath  and it will be
considered  as the global path

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

deploy/cephfs/kubernetes/csi-cephfsplugin.yaml

@@ -38,7 +38,7 @@ spec:
                 fieldRef:
                   fieldPath: spec.nodeName
           volumeMounts:
-            - name: plugin-dir
+            - name: socket-dir
               mountPath: /csi
             - name: registration-dir
               mountPath: /registration
@@ -73,13 +73,13 @@ spec:
           volumeMounts:
             - name: mount-cache-dir
               mountPath: /mount-cache-dir
-            - name: plugin-dir
+            - name: socket-dir
               mountPath: /csi
-            - name: csi-plugins-dir
-              mountPath: /var/lib/kubelet/plugins/kubernetes.io/csi
-              mountPropagation: "Bidirectional"
-            - name: pods-mount-dir
+            - name: mountpoint-dir
               mountPath: /var/lib/kubelet/pods
+              mountPropagation: Bidirectional
+            - name: plugin-dir
+              mountPath: /var/lib/kubelet/plugins
               mountPropagation: "Bidirectional"
             - name: host-sys
               mountPath: /sys
@@ -93,21 +93,21 @@ spec:
       volumes:
         - name: mount-cache-dir
           emptyDir: {}
-        - name: plugin-dir
+        - name: socket-dir
           hostPath:
             path: /var/lib/kubelet/plugins/cephfs.csi.ceph.com/
             type: DirectoryOrCreate
-        - name: csi-plugins-dir
-          hostPath:
-            path: /var/lib/kubelet/plugins/kubernetes.io/csi
-            type: DirectoryOrCreate
         - name: registration-dir
           hostPath:
             path: /var/lib/kubelet/plugins_registry/
             type: Directory
-        - name: pods-mount-dir
+        - name: mountpoint-dir
           hostPath:
             path: /var/lib/kubelet/pods
+            type: DirectoryOrCreate
+        - name: plugin-dir
+          hostPath:
+            path: /var/lib/kubelet/plugins
             type: Directory
         - name: host-sys
           hostPath: