feat: add artifact-keeper

- converted the artifact-keeper helm-chart into kustomization manifests
- converted postgres to cnpg
- moved secrets to vault

apps/base/artifact-keeper/serviceaccount_backend.yaml

@@ -0,0 +1,11 @@
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: backend
+  namespace: artifact-keeper
+  labels:
+    app.kubernetes.io/name: artifact-keeper
+    app.kubernetes.io/instance: ak
+    app.kubernetes.io/part-of: artifact-keeper
+    app.kubernetes.io/component: backend