cue modules: move stdlib to pkg/alpha.dagger.io

In preparation for Europa, we will vendor multiple CUE modules:

- `pkg/alpha.dagger.io`: legacy non-europa packages
- `pkg/dagger.io`: core Europa packages
- `pkg/universe.dagger.io`: Europa universe

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

pkg/alpha.dagger.io/kubernetes/kustomize/tests/kustomize.cue

@@ -0,0 +1,31 @@
+package kustomize
+
+import (
+	"encoding/yaml"
+	"alpha.dagger.io/dagger"
+)
+
+TestKustomize: {
+	testdata: dagger.#Artifact
+
+	// Run Kustomize
+	kustom: #Kustomize & {
+		source:        testdata
+		kustomization: yaml.Marshal({
+			resources: ["deployment.yaml", "pod.yaml"]
+			images: [{
+				name:   "nginx"
+				newTag: "v1"
+			}]
+			replicas: [{
+				name:  "nginx-deployment"
+				count: 2
+			}]
+		})
+	}
+
+	// Verify kustomization generation
+	verify: #VerifyKustomize & {
+		source: kustom
+	}
+}