Move github.com/rancher/rancher/pkg/namespace to types

The namespace package contains constants that need to be used
globally so moving to types to other go modules can depend on it.

namespace/namespace.go

@@ -0,0 +1,18 @@
+package namespace
+
+import v1 "k8s.io/api/core/v1"
+
+var projectIDAnnotation = "field.cattle.io/projectId"
+
+func NsByProjectID(obj interface{}) ([]string, error) {
+	ns, ok := obj.(*v1.Namespace)
+	if !ok {
+		return []string{}, nil
+	}
+
+	if id, ok := ns.Annotations[projectIDAnnotation]; ok {
+		return []string{id}, nil
+	}
+
+	return []string{}, nil
+}