Return list of copied files to support atomic copy+move

[nicolasreichel]

Hi, I think it would be great if rclone.copy/rclone.copyto/rclone.sync were to return a list of affected files at the end. This would allow for atomic copy+move (copying a set of files followed by moving those exact same files) whilst still using the efficient batch mode. Currently you'd have to do something like rclone.lsjson and a per-file copy, or accept that the bulk copy+move is not atomic. This copy+move pattern is a common use case in transfer orchestration.

I can fork and submit a PR with a suggested implementation if that's helpful?

Thanks for the nice wrapper library!