M5: notifications, setup check, audit log and password confirmation

- notifications to administrators for failed backup/restore runs and
  locations without a successful backup for two days (once a day)
- setup check in the admin overview: error when the key/kit is not set
  up, warning for missing, old or failed backups
- security events (recovery kit downloaded, location removed,
  append-only turned off, retention changed, snapshots forgotten) go to
  the audit log and are announced to all administrators, from the web
  and from occ; the scheduled weekly cleanup is logged only
- fix: the recovery-kit download link failed the CSRF check (412); it
  now requires a recent password confirmation instead, like creating the
  key, removing a location and restoring

lib/BackgroundJob/RestoreJob.php

@@ -23,6 +23,7 @@ class RestoreJob extends QueuedJob {
 		private TargetService $targets,
 		private RestoreService $restore,
 		private LoggerInterface $logger,
+		private \OCA\NgBackup\Service\AlertService $alerts,
 	) {
 		parent::__construct($time);
 	}
@@ -46,6 +47,7 @@ class RestoreJob extends QueuedJob {
 			$this->logger->error('NG Backup restore ' . $run->getId() . ' failed: ' . $e->getMessage(), ['exception' => $e]);
 			$run->setStatus(Run::FAILED);
 			$run->setError($e->getMessage());
+			$this->alerts->runFailed($run, '#' . $run->getTargetId());
 		}
 		$run->setFinishedAt(time());
 		$run->setUpdatedAt(time());