(timebox) Explore resume/upload / make the chunking work on S3 direct upload

Investigate uploads using the S3 provider for direct uploads.

Q/A:

1. How to know if the Amazon S3 addon is installed and enabled on the server?
2. How to retrieve S3 data (bucket, credentials)?
   => Amazon S3 Direct Upload for Web UI.
3. How to upload a file using the S3 SDK for Python?
   => Done using boto3.
4. How to use callbacks to keep Drive updated with progress bars?
   => Same link as above.
5. Can we improve the Python client to use the S3 provider when available? And so Drive will have near to nothing to change in its core.
   => Yes, a snippet can be found in comments.