Bug 870171 - Part 12: Add HealthReportPruneService skeleton.
Bug 870171 - Part 13: Validate prune intent.
Bug 870171 - Part 14: Add PrunePolicy skeletion.
Bug 870171 - Part 15: Add attemptPruneByDuration.
Bug 870171 - Part 16: Add attemptPruneBySize.