Improve config package names and reduce API exposure.

api/konfig/builtinpluginconsts/namespace.go

@@ -0,0 +1,16 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package builtinpluginconsts
+
+const (
+	namespaceFieldSpecs = `
+namespace:
+- path: metadata/namespace
+  create: true
+- path: subjects
+  kind: RoleBinding
+- path: subjects
+  kind: ClusterRoleBinding
+`
+)