Is there an existing issue for this?

• I have searched existing issues, it hasn't been reported yet

Use case description

Support a further accessConfigurations: CLIENT_CERTIFICATE_TLS_AUTH) to allow configuring mTLS-authenticated lambda event sources

https://docs.aws.amazon.com/lambda/latest/dg/with-kafka.html#services-smaa-topic-add
https://aws.amazon.com/about-aws/whats-new/2021/11/aws-lambda-supports-mtls-authentication-amazon-msk-event-source/
https://aws.amazon.com/blogs/compute/introducing-mutual-tls-authentication-for-amazon-msk-as-an-event-source/

I'm happy to have a look at a PR for this?