deploy encapi to au-syd1

encapi is the new Postgres-backed Puppet ENC replacing Cobbler. Stand it up in
k8s alongside artifactapi so the puppet masters (via encapi-cli classify) and
the enc_direct_facts fact can reach it at encapi.k8s.syd1.au.unkin.net.

- add apps/base/encapi: namespace, deployment (git.unkin.net/unkin/encapi), service,
  gateway + httproute (encapi.k8s.syd1.au.unkin.net), configmap, CNPG cluster +
  pooler (db encapi), VaultAuth + VaultStaticSecrets (postgres-credentials, environment)
- add apps/overlays/au-syd1/encapi overlay
- register apps/overlays/*/encapi in the platform ApplicationSet

Note: the Vault KV secrets kv/kubernetes/namespace/encapi/default/{postgres-credentials,
environment} must be seeded before first sync; 'environment' carries DBPASS (matching
the CNPG owner password) and ENCAPI_WRITE_TOKEN.

argocd/applicationsets/platform.yaml

@@ -21,6 +21,7 @@ spec:
       - path: apps/overlays/*/cnpg-system
       - path: apps/overlays/*/consul
       - path: apps/overlays/*/elastic-system
+      - path: apps/overlays/*/encapi
       - path: apps/overlays/*/externaldns
       - path: apps/overlays/*/inteldeviceplugins-system
       - path: apps/overlays/*/jfrog