Add separate backup tags for instance and EBS additional volumes

Actually, Backup tag is spread as Instance tag but also as an EBS tag. This leads to a duplicate backup of volumes by AWS Backup service. Adding 2 separated tag for instance and EBS volumes, allow user to choose which strategy (s)he wants to as a Backup. (s)he still can keep the original mechanism by setting instance_backup_policy and ebs_backup_policy as inputs.