CI: Migrate S3 actions locally from personal repos

[jwagantall]

Hosting the code for seemethere/download-artifact-s3 and seemethere/upload-artifact-s3 locally to encorage more coolaboration and maintainance of this action. This first migration is based on v4.2.0

Issue: pytorch/ci-infra#242

[vercel[bot]]

@jwagantall is attempting to deploy a commit to the Meta Open Source Team on Vercel.

A member of the Team first needs to authorize it.

[jwagantall]

Creating this consolidated PR (with unit tests) that covers: https://github.com/pytorch/test-infra/pull/6157 https://github.com/pytorch/test-infra/pull/6158

This PR was created in case the team would prefer to do this migration as a whole instead of sequential PRs

[github-advanced-security[bot]]

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[zxiiro]

@seemethere @malfet can you review this latest attempt at importing the artifact download/upload actions? any concerns with this approach?