Add a PhutilAWSS3Future class
Summary: Ref T5155. This doesn't do anything currently, but should allow us to perform S3 operations without the Amazon S3 PHP Class.
Test Plan: I'm not really sure how to test this... if you have any ideas then please let me know.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: epriestley, Korvin
Maniphest Tasks: T5155
Differential Revision: https://secure.phabricator.com/D9781