Acceptance criteria

• Introduce new internal ScyllaDBManagerClusterRegistration API
• Add validation of ScyllaDBManagerClusterRegistrations, limited to objects with a predefined label (used as selector by the controller)
• Extend Scylla Operator with a controller creating ScyllaDBManagerClusterRegistration objects for ScyllaDBDatacenters with a predefined labels
  • Delete the internal object in case of ScyllaDBDatacenter deletion or predefined label removal: Scylla Manager controller should remove clusters from manager state on object deletion #1930
• Extend Scylla Operator with a ScyllaDBManagerClusterRegistration controller registering ScyllaDBDatacenters with global ScyllaDB Manager instance
  • Includes auth token management
  • Includes blocking until the cluster is available
  • Includes finalizer for deregistering ScyllaDBDatacenter
• Add an E2E test for registering and deregistering ScyllaDBDatacenters with global ScyllaDB Manager instance.