Backup file kinds

enum _PRL_BACKUP_FILE_KIND {
  PBFK_UNKNOWN = 0,
  PBFK_DISK_IMAGE = 1,
  PBFK_DISK_CONFIG = 2,
  PBFK_VM_CONFIG = 3,
  PBFK_LOG = 4,
  PBFK_SYMLINK = 5
};