Add support for Amazon s3 bucket package storage "paths"

Has anyone tried distributing rez packages using s3 buckets?

Has anyone tried using other cloud storage systems to distribute rez packages?

Amazon s3 buckets are a fairly inexpensive, accessible, and secure way to distribute files to multiple locations, especially compared to some of the other cloud storage solutions. Plus, they support billing to the receiver, allowing one group to publish buckets, but not have to be on the hook for all the access and transfer.

The issue names no files, tests, or entry points. First clarify the expected Amazon S3 bucket storage-path behavior and whether other cloud storage systems are in scope; completion should be defined as documented, working support for the agreed package-distribution paths.

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