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

src/components/Locations.vue

@@ -47,6 +47,8 @@ import NcPasswordField from '@nextcloud/vue/components/NcPasswordField'
 import NcSelect from '@nextcloud/vue/components/NcSelect'
 import NcSettingsSection from '@nextcloud/vue/components/NcSettingsSection'
 import NcTextField from '@nextcloud/vue/components/NcTextField'
+import { confirmPassword } from '@nextcloud/password-confirmation'
+import '@nextcloud/password-confirmation/style.css'
 import api from '../api.js'
 
 defineProps({ status: { type: Object, required: true } })
@@ -107,7 +109,13 @@ async function remove(target) {
 	if (!window.confirm(t('ng_backup', 'Remove "{name}" from NG Backup? The backups on the location itself are kept.', { name: target.name }))) {
 		return
 	}
-	await api.removeTarget(target.id)
+	try {
+		await confirmPassword()
+		await api.removeTarget(target.id)
+	} catch (e) {
+		error.value = e?.message || ''
+		return
+	}
 	emit('changed')
 }
 </script>