Unregister csiplugin even if socket path is gone

Signed-off-by: Ted Yu <yuzhihong@gmail.com>

pkg/kubelet/pluginmanager/cache/actual_state_of_world.go

@@ -75,6 +75,18 @@ type actualStateOfWorld struct {
 
 var _ ActualStateOfWorld = &actualStateOfWorld{}
 
+// NamedPluginHandler holds information for handler and the name of the plugin
+type NamedPluginHandler struct {
+	Handler PluginHandler
+	Name    string
+}
+
+// SocketPluginHandlers contains the map from socket path to NamedPluginHandler
+type SocketPluginHandlers struct {
+	Handlers map[string]NamedPluginHandler
+	sync.Mutex
+}
+
 // PluginInfo holds information of a plugin
 type PluginInfo struct {
 	SocketPath string