Resolve "Update gRPC abstraction API with missing calls and refactoring"

cli/cmd/pndCreate.go

cli/cmd/pndList.go

controller/api/api_test.go

controller/api/app.go

controller/api/configurationManagement.go

controller/api/managedNetworkElement.go

controller/api/plugin.go

controller/api/pnd.go

controller/northbound/client/app.go

controller/northbound/client/configurationManagement.go

controller/northbound/server/networkElement.go

controller/nucleus/pndFilesystemStore.go