GitLab

* NAS-117233: New Google Cloud Storage task field: bucket_policy_only

* NAS-117233: Show checkbox only for providers of type Google Cloud Storage

* NAS-117233: Create CloudsyncProviderName enum

* NAS-117233: bucket_policy_only checkbox defaults to false
Co-authored-by: Boris Vasilenko <bvasilenko@ixsystems.com>