Improve command package isolation.

pkg/commands/build/testdata/testcase-single-overlay/in/package/kustomization.yaml

@@ -0,0 +1,19 @@
+namePrefix: team-foo-
+commonLabels:
+  app: mynginx
+  org: example.com
+  team: foo
+commonAnnotations:
+  note: This is a test annotation
+resources:
+  - deployment.yaml
+  - service.yaml
+configMapGenerator:
+  - name: configmap-in-base
+    literals:
+      - foo=bar
+secretGenerator:
+- name: secret-in-base
+  commands:
+    username: "printf admin"
+    password: "printf somepw"