[Feature] Adopt Kubernetes recommended labels

[gbartolini]

Following cloudnative-pg/cloudnative-pg#8087, Barman Cloud Plugin should apply the Kubernetes recommended labels to every object managed by it.

• app.kubernetes.io/name: barman-cloud-plugin
• app.kubernetes.io/instance: (where applicable)
• app.kubernetes.io/version:
• app.kubernetes.io/component: database
• app.kubernetes.io/managed-by: cloudnative-pg