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/go-openapi/swag/jsonutils/concat.go

@@ -0,0 +1,92 @@
+// SPDX-FileCopyrightText: Copyright 2015-2025 go-swagger maintainers
+// SPDX-License-Identifier: Apache-2.0
+
+package jsonutils
+
+import (
+	"bytes"
+)
+
+// nullJSON represents a JSON object with null type
+var nullJSON = []byte("null")
+
+const comma = byte(',')
+
+var closers map[byte]byte
+
+func init() {
+	closers = map[byte]byte{
+		'{': '}',
+		'[': ']',
+	}
+}
+
+// ConcatJSON concatenates multiple json objects or arrays efficiently.
+//
+// Note that [ConcatJSON] performs a very simple (and fast) concatenation
+// operation: it does not attempt to merge objects.
+func ConcatJSON(blobs ...[]byte) []byte {
+	if len(blobs) == 0 {
+		return nil
+	}
+
+	last := len(blobs) - 1
+	for blobs[last] == nil || bytes.Equal(blobs[last], nullJSON) {
+		// strips trailing null objects
+		last--
+		if last < 0 {
+			// there was nothing but "null"s or nil...
+			return nil
+		}
+	}
+	if last == 0 {
+		return blobs[0]
+	}
+
+	var opening, closing byte
+	var idx, a int
+	buf := bytes.NewBuffer(nil)
+
+	for i, b := range blobs[:last+1] {
+		if b == nil || bytes.Equal(b, nullJSON) {
+			// a null object is in the list: skip it
+			continue
+		}
+		if len(b) > 0 && opening == 0 { // is this an array or an object?
+			opening, closing = b[0], closers[b[0]]
+		}
+
+		if opening != '{' && opening != '[' {
+			continue // don't know how to concatenate non container objects
+		}
+
+		const minLengthIfNotEmpty = 3
+		if len(b) < minLengthIfNotEmpty { // yep empty but also the last one, so closing this thing
+			if i == last && a > 0 {
+				_ = buf.WriteByte(closing) // never returns err != nil
+			}
+			continue
+		}
+
+		idx = 0
+		if a > 0 { // we need to join with a comma for everything beyond the first non-empty item
+			_ = buf.WriteByte(comma) // never returns err != nil
+			idx = 1                  // this is not the first or the last so we want to drop the leading bracket
+		}
+
+		if i != last { // not the last one, strip brackets
+			_, _ = buf.Write(b[idx : len(b)-1]) // never returns err != nil
+		} else { // last one, strip only the leading bracket
+			_, _ = buf.Write(b[idx:])
+		}
+		a++
+	}
+
+	// somehow it ended up being empty, so provide a default value
+	if buf.Len() == 0 && (opening == '{' || opening == '[') {
+		_ = buf.WriteByte(opening) // never returns err != nil
+		_ = buf.WriteByte(closing)
+	}
+
+	return buf.Bytes()
+}