Deploy cephrgw-operator to cephrgw-system

The cephrgw-operator provisions Ceph RGW (S3) buckets and access keys from
CRDs via the Ceph manager dashboard API. Deploy it as a platform app.

- Add apps/base/cephrgw-system: namespace, ServiceAccount + ClusterRole/
  Binding (manage ceph.unkin.net CRDs, Secrets, leases), and the operator
  Deployment. CRDs are pulled from the operator repo at tag v0.1.0; the
  Deployment sources dashboard credentials from the cephrgw-credentials
  Secret via envFrom and carries the reloader annotation.
- Add apps/overlays/au-syd1/cephrgw-system referencing the base.
- Register apps/overlays/*/cephrgw-system in the platform ApplicationSet.

The platform AppProject already permits *-system namespaces and the
Namespace/ClusterRole/CRD cluster resources, so no project change is needed.
Requires the cephrgw-credentials Secret to be created out-of-band (see the
operator's docs/ceph-setup.md); it is intentionally not managed in GitOps.

apps/base/cephrgw-system/rbac.yaml

@@ -0,0 +1,38 @@
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: cephrgw-operator
+  namespace: cephrgw-system
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: cephrgw-operator
+rules:
+  - apiGroups: ["ceph.unkin.net"]
+    resources: ["*"]
+    verbs: ["*"]
+  # The operator delivers RGW access/secret keys into Secrets.
+  - apiGroups: [""]
+    resources: ["secrets"]
+    verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]
+  - apiGroups: [""]
+    resources: ["events"]
+    verbs: ["create", "patch"]
+  - apiGroups: ["coordination.k8s.io"]
+    resources: ["leases"]
+    verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: cephrgw-operator
+subjects:
+  - kind: ServiceAccount
+    name: cephrgw-operator
+    namespace: cephrgw-system
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: cephrgw-operator