Add helm charts for cluster tasks and run tasks with a job

chart/cluster-tasks/Chart.yaml

chart/cluster-tasks/templates/clear-cache.yaml

chart/cluster-tasks/templates/database-backup.yaml

chart/cluster-tasks/templates/database-restore.yaml

chart/cluster-tasks/values.yaml

examples/clear-cache-taskrun.yaml

examples/database-backup-taskrun.yaml

examples/database-restore-taskrun.yaml

examples/publish-unpublish-taskrun.yaml

roles/role.yaml

tasks/publish-unpublish.yaml