Kinesis worker doesn't use amazonica credentials mechanism

[Limess]

Current amazonica.aws.kinesis/worker doesn't use amazonica.core/credentials or amazonica.core/*credentials* - it instead explicitly needs credentials to be provided.

This was a minor pain when setting up a shim to the AWS SDK V2 to support AWS SSO (https://github.com/signal-ai/amazonica-aws-sso) as I had to create a separate provider and wire it through.