REFACTOR(repo): move vault/ to manifests/

- Move ExternalSecret files from vault/ to manifests/secret.yaml
- Merge multiple secrets with --- separator (postgresql)
- Update kustomization.yaml references
- Remove vault/ folders

Apps: postgresql, postgresql-dev, pgweb, minio, velero

postgresql-dev/kustomization.yaml

@@ -1,4 +1,4 @@
 apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
 resources:
-- vault/postgresql-password-dev.yaml
+- manifests/secret.yaml