feat(publisher-s3): Add sessionToken and change default fallback

[bboure]

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• The changes are appropriately documented (if applicable).
• The changes have sufficient test coverage (if applicable).
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Summarize your changes:

• add a sessionToken option
• change the fallback to use the credential provider chain

Fixes #2983

[codecov]

Codecov Report

Merging #2984 (9969f8b) into main (bb29cd5) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #2984   +/-   ##
=======================================
  Coverage   73.78%   73.78%           
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  Files          66       66           
  Lines        2144     2144           
  Branches      423      423           
=======================================
  Hits         1582     1582           
  Misses        357      357           
  Partials      205      205           

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[VerteDinde]

Thanks for the PR! Could we re-add the process.env fallbacks here, so that these are included if they're not in the config (CI could be a use case here)?

[riywo]

This GitHub Action does use environment variables! https://github.com/aws-actions/configure-aws-credentials

[bboure]

@VerteDinde if the credentials are not in the config and present in the process.env, the SDK will use them without needing to pass them explicitly.

THis is the recommended way. See doc