Add test for kube-gcp cue-manifest step

Signed-off-by: Tom Chauveau <tom.chauveau@epitech.eu>

docs/learn/tests/kube-gcp/cue-manifest/manifest.cue

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"encoding/yaml"
+)
+
+// Define and generate kubernetes deployment to deploy to kubernetes cluster
+#AppManifest: {
+	// Name of the application
+	name: string
+
+	// Image to deploy to
+	image: string
+
+	// Define a kubernetes deployment object
+	deployment: #Deployment & {
+		"name":  name
+		"image": image
+	}
+
+	// Define a kubernetes service object
+	service: #Service & {
+		"name": name
+		ports: http: deployment.port
+	}
+
+	// Merge definitions and convert them back from CUE to YAML
+	manifest: yaml.MarshalStream([deployment.manifest, service.manifest])
+}