e2e framework: add NamespacedName

The E2E framework contains several functions which only differ in how they get
name and namespace: from an API object (WaitForPodRunningInNamespace) or as
separate parameters (WaitTimeoutForPodRunningInNamespace).

NamespacedName and the NamedObject interface enable writing helper functions
that can be called with both an API object (like *v1.Pod, which implements
Object and thus NamedObject) and name+namespace string (via
NamespacedName).

The other advantage of NamespacedName is that the order of name and namespace
parameter cannot be mixed up.

NamespacedName was derived from k8s.io/apimachinery/pkg/types.NamespacedName. A
separate type in the framework package was chosen a) to avoid additional
imports in test code and b) because the interface might not be suitable for
k8s.io/apimachinery.

test/e2e/framework/namespacedname.go

@@ -0,0 +1,49 @@
+/*
+Copyright 2023 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package framework
+
+// NamespacedName comprises a resource name, with a mandatory namespace,
+// rendered as "<namespace>/<name>". It implements NamedObject and thus can be
+// used as function parameter instead of a full API object.
+type NamespacedName struct {
+	Namespace string
+	Name      string
+}
+
+var _ NamedObject = NamespacedName{}
+
+// NamedObject is a subset of metav1.Object which provides read-only access
+// to name and namespace of an object.
+type NamedObject interface {
+	GetNamespace() string
+	GetName() string
+}
+
+// GetNamespace implements NamedObject.
+func (n NamespacedName) GetNamespace() string {
+	return n.Namespace
+}
+
+// GetName implements NamedObject.
+func (n NamespacedName) GetName() string {
+	return n.Name
+}
+
+// String returns the general purpose string representation
+func (n NamespacedName) String() string {
+	return n.Namespace + "/" + n.Name
+}