## What this PR does
This patch creates a new backups.cozystack.io API group which includes
backup-related resources owned exclusively by Cozystack core. A
cronjob-like controller is implemented to create backup jobs that will
be handled by appropriate third-party or external controllers.
### Release note
```release-note
[backups] Implement the core backup API and an accompanying controller.
```
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## Summary by CodeRabbit
* **New Features**
* Adds a full backups system: create scheduled Plans (cron), run
BackupJobs with lifecycle phases (Pending→Running→Succeeded/Failed), and
produce Backup artifacts with metadata.
* Adds RestoreJobs to restore from stored Backups and track restore
progress/status.
* Exposes new API resources (Plan, BackupJob, Backup, RestoreJob) so
backups and restores can be declared and observed via the platform.
<sub>✏️ Tip: You can customize this high-level summary in your review
settings.</sub>
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
(cherry picked from commit 67ecf3d0f6)
Signed-off-by: Timofei Larkin <lllamnyp@gmail.com>
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