feat: Add support for IRSA and aws default provider chain.

[zachaller]

This allow you to set s3 configuration useSDKCreds: true to tell the
exec image to pull configuration from IRSA environment variables, or any supported aws sdk credentials following the default priority order

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this is a chore.
• The title of the PR is (a) conventional, (b) states what changed, and (c) suffixes the related issues number. E.g. "fix(controller): Updates such and such. Fixes #1234".
• I have written unit and/or e2e tests for my change. PRs without these are unlike to be merged.
• Optional. I've added My organization is added to the USERS.md.
• I've signed the CLA and required builds are green.

[zachaller]

This will depend on argoproj/pkg#13

[alexec]

I've merged the related PR to move you forward.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@47bc6f3). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #2468   +/-   ##
=========================================
  Coverage          ?   11.23%           
=========================================
  Files             ?       73           
  Lines             ?    30852           
  Branches          ?        0           
=========================================
  Hits              ?     3465           
  Misses            ?    26920           
  Partials          ?      467

Impacted Files	Coverage Δ
pkg/apis/workflow/v1alpha1/workflow_types.go	6.3% <ø> (ø)

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[zachaller]

@alexec I think this looks good now, let me know if there is something I missed?