feat(plugins/aws-lambda): support Lambda response streaming

[DiscreteTom]

Summary

Make the aws-lambda plugin to support Lambda response streaming.

Moved from #13171 due to the branch is renamed to fit the naming scheme.

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]

[tysoekong]

Here @DiscreteTom is the updated SDK: Kong/lua-resty-aws#119

If you use this newer version of the SDK, you should receive an extra table param back from the AWS execute function body_reader which comes from the res object.

You can use this to read each chunk back to the client. Decode of the chunk is still manual, because it is a bit more rework to turn execute_request into a weird optional iterator.

Does this work for your Lambda plugin enhancement so far?