Add support for EKS IRSA authentication to the LLM Bedrock driver

[vl-kp]

Summary

Add support for EKS IRSA authentication to the LLM Bedrock driver without access key id and secret key

Checklist

• The Pull Request has tests
• A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Issue reference

Fix #[issue number]

[CLAassistant]

All committers have signed the CLA.

[windmgc]

Hi @vl-kp I think this does not need to be explicitly specified here as the EKS IRSA is checked by the underlying SDK automatically. Is there any issue you encounter when running Kong with an EKS environment with IRSA configured?

[vl-kp]

@windmgc last time i found it is not working when running in EKS with IRSA role for this plugin

[windmgc]

@vl-kp It should be able to work with IRSA out of the box, feel free to create an issue with your debug level log so that we can analyze further