Proposed title of this feature request
Add --dry-run parameter in Velero CLI when creating/restoring backups.

What is the nature and description of the request?
Add the --dry-run parameter in Velero CLI when creating/restoring backups, to preview the resources that will be backed-up or restored before executing the regular backup or restore command.

There is an upstream issue https://github.com/vmware-tanzu/velero/issues/448 similar to this request

Why does the customer need this? (List the business requirements here)
This feature will be used to have a look into the resources that will be backed-up or restored, prior to execute the regular backup/restore command.

Optional: List affected component/s.