Add ability to limit bandwidth for S3 uploads/downloads

Problem

Original from #1078, this is a feature request to add the ability for the `aws s3` commands to limit the amount of bandwidth used for uploads and downloads. In the referenced issue, it was specifically mentioned that some ISPs charge fees if you go above a specific mbps, so users need the ability to limit bandwidth. I imagine this is something we'd only need to add to the `aws s3` commands.