Implement autobackup-operator controllers, tests, CI and packaging

PVCs and CloudNativePG Clusters need S3 buckets and backup schedules
provisioned consistently. This operator watches the
backups.unkin.net/{schedule,destination} annotations on those objects and
provisions everything needed to back them up, with no new CRDs.

- Add a PVC controller that provisions cephrgw ObjectStoreUser/Bucket/BucketAccess,
  auto-generates a restic repo-password Secret and creates a k8up Schedule scoped
  to the PVC via spec.backup.volumes[].persistentVolumeClaim.claimName.
- Add a CNPG Cluster controller that provisions the same bucket stack, idempotently
  patches spec.backup.barmanObjectStore (leaving a user-set destinationPath alone
  with a Warning event) and creates a ScheduledBackup.
- Resolve destinations through a ConfigMap lookup table; requeue until the
  BucketAccess is Ready before creating schedule resources; own-reference created
  resources and retain bucket data by default.
- Add schedule-mapping helpers (k8up 5-field/shortcut pass-through, CNPG 6-field
  seconds-first) and deterministic, length-bounded name derivation.
- Add unit tests (schedule mapping, name derivation, destination resolution) and
  envtest controller tests for both paths, wiring the external CRDs into envtest.
- Add kubebuilder-generated RBAC, a Dockerfile (distroless/nonroot), Woodpecker
  lint/test/build pipelines and a tag-triggered image push to the artifactapi
  docker-internal registry, plus a version-bump Makefile and deploy manifests.

vendor/github.com/google/gnostic-models/extensions/extensions.go

@@ -0,0 +1,64 @@
+// Copyright 2017 Google LLC. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gnostic_extension_v1
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/known/anypb"
+)
+
+type extensionHandler func(name string, yamlInput string) (bool, proto.Message, error)
+
+// Main implements the main program of an extension handler.
+func Main(handler extensionHandler) {
+	// unpack the request
+	data, err := ioutil.ReadAll(os.Stdin)
+	if err != nil {
+		log.Println("File error:", err.Error())
+		os.Exit(1)
+	}
+	if len(data) == 0 {
+		log.Println("No input data.")
+		os.Exit(1)
+	}
+	request := &ExtensionHandlerRequest{}
+	err = proto.Unmarshal(data, request)
+	if err != nil {
+		log.Println("Input error:", err.Error())
+		os.Exit(1)
+	}
+	// call the handler
+	handled, output, err := handler(request.Wrapper.ExtensionName, request.Wrapper.Yaml)
+	// respond with the output of the handler
+	response := &ExtensionHandlerResponse{
+		Handled: false, // default assumption
+		Errors:  make([]string, 0),
+	}
+	if err != nil {
+		response.Errors = append(response.Errors, err.Error())
+	} else if handled {
+		response.Handled = true
+		response.Value, err = anypb.New(output)
+		if err != nil {
+			response.Errors = append(response.Errors, err.Error())
+		}
+	}
+	responseBytes, _ := proto.Marshal(response)
+	os.Stdout.Write(responseBytes)
+}