Make uploads and downloads restartable

[bernd-wechner]

For large files in particular there's a real risk that a transfer is interrupted. For that reason most web tech today and the Google Cloud Store in particular support restartable downloads and uploads.

This CLI would need to do something in prep to exploit that, which needs a little research and testing of ideas. It may fall flat if it requires the Google Cloud Store private key to work, as that is in Degoo's hands, we can't interact freely with the cloud store only via the Degoo GraphQL interface and that's only doable if their web interface implements a restartable download/upload that can be watched. I'm not sure it does.