enhancement(sinks): allow to provide aws session token

[anil-db]

Summary

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

How did you test this PR?

when using aws access and secret keys sometime session token is also required if these access token is temporary.
mechanism of getting the temporary token and renew the token is external to vector. external system uses secret backend mechanism to let vector know the new set of tokens.

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR.

Notes

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References

[pront]

Thank you @anil-db