FEAT(minio): add ClusterExternalSecret for S3 credentials

- Add minio-s3-credentials ClusterExternalSecret
- Auto-create secret in namespaces with minio-s3: enabled label
- Add minio-s3 label to zot namespace via managedNamespaceMetadata
- Credentials stored in Vault at secret/minio-s3-credentials

minio/manifests/secret.yaml

@@ -28,3 +28,37 @@ spec:
       remoteRef:
         key: minio
         property: ROOT_PASSWORD
+---
+apiVersion: external-secrets.io/v1
+kind: ClusterExternalSecret
+metadata:
+  name: minio-s3-credentials
+spec:
+  namespaceSelector:
+    matchLabels:
+      minio-s3: enabled
+  refreshInterval: 1h
+  externalSecretSpec:
+    secretStoreRef:
+      kind: ClusterSecretStore
+      name: vault-backend
+    target:
+      name: minio-s3-credentials
+      creationPolicy: Owner
+    data:
+      - secretKey: AWS_ACCESS_KEY_ID
+        remoteRef:
+          key: minio-s3-credentials
+          property: AWS_ACCESS_KEY_ID
+      - secretKey: AWS_SECRET_ACCESS_KEY
+        remoteRef:
+          key: minio-s3-credentials
+          property: AWS_SECRET_ACCESS_KEY
+      - secretKey: AWS_REGION
+        remoteRef:
+          key: minio-s3-credentials
+          property: AWS_REGION
+      - secretKey: AWS_S3_ENDPOINT
+        remoteRef:
+          key: minio-s3-credentials
+          property: AWS_S3_ENDPOINT