[Suggestion] Add destination folder for external backup

[Fakhri1999]

I suggest having the option to set the destination folder for external backup. In the latest version (DriveBackupV2-1.4.0), the external backup folder will always in the folder external-backup/ftp-connection-name.

I suggest adding a key in each external-backup-list, maybe a destination key for storing the destination folder for this external backup entry. Each entry has its own destination key