Implement exponential backoff in utils/upload_file function

[karolisr]

I ran into a problem while uploading a large number of files to my university's managed Google Drive: HttpError 403 "User rate limit exceeded." Google suggests an exponential backoff strategy to resolve this: https://developers.google.com/drive/api/v3/handle-errors#resolve_a_403_error_user_rate_limit_exceeded. I have implemented a rudimentary solution in my fork of the repo: https://github.com/karolisr/drive-cli/blob/550bf14c53ebfbcb0007ef2ca2b2ff7be46fe5a8/drive_cli/utils.py#L381. If you would like I could clean up other changes and push this code to the dev branch here. Additionally, if there are problems with the code I am proposing, please let me know how you would like me to resolve them.

Thanks