Local file support

[mcandre]

Please make sure to support local files as sources and targets.

Unfortunately, Kubernetes file transfer can be quite slow. So copying files first from S3 to local disk, then local disk to Kubernetes, would often be more reliable. You can restart the file transfer without having to keep requesting the same data over and over from S3, which reduces overhead for every single file transferred.

If you must have a URI scheme, then use file://, e.g. file:///Users/andrew/Downloads/coolbeans.txt