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.

apps/base/encapi/gateway.yaml

@@ -0,0 +1,37 @@
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: Gateway
+metadata:
+  labels:
+    traefik.io/instance: internal
+  annotations:
+    cert-manager.io/cluster-issuer: vault-issuer
+    cert-manager.io/common-name: encapi.k8s.syd1.au.unkin.net
+    cert-manager.io/private-key-size: "4096"
+    external-dns.alpha.kubernetes.io/hostname: encapi.k8s.syd1.au.unkin.net
+    external-dns.alpha.kubernetes.io/target: 198.18.200.4
+  name: encapi
+  namespace: encapi
+spec:
+  gatewayClassName: traefik-internal
+  listeners:
+    - allowedRoutes:
+        namespaces:
+          from: Same
+      hostname: encapi.k8s.syd1.au.unkin.net
+      name: http
+      port: 80
+      protocol: HTTP
+    - allowedRoutes:
+        namespaces:
+          from: Same
+      hostname: encapi.k8s.syd1.au.unkin.net
+      name: https
+      port: 443
+      protocol: HTTPS
+      tls:
+        certificateRefs:
+          - group: ""
+            kind: Secret
+            name: encapi-tls
+        mode: Terminate