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/sigs.k8s.io/controller-runtime/pkg/client/codec.go

@@ -0,0 +1,40 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+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 client
+
+import (
+	"errors"
+	"net/url"
+
+	"k8s.io/apimachinery/pkg/conversion/queryparams"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+var _ runtime.ParameterCodec = noConversionParamCodec{}
+
+// noConversionParamCodec is a no-conversion codec for serializing parameters into URL query strings.
+// it's useful in scenarios with the unstructured client and arbitrary resources.
+type noConversionParamCodec struct{}
+
+func (noConversionParamCodec) EncodeParameters(obj runtime.Object, to schema.GroupVersion) (url.Values, error) {
+	return queryparams.Convert(obj)
+}
+
+func (noConversionParamCodec) DecodeParameters(parameters url.Values, from schema.GroupVersion, into runtime.Object) error {
+	return errors.New("DecodeParameters not implemented on noConversionParamCodec")
+}