IoT credentials provider

**Is your feature request related to a problem? Please describe.**
We have dug through the code to look for IoT credentials provider, but we could not find any.
Our use case is to give IoT devices limited credentials to S3 buckets.

**Describe the solution you'd like**
An wrapper that performs something similar to this
https://docs.aws.amazon.com/iot/latest/developerguide/authorizing-direct-aws.html
Or the implementation similar to the ones used in KVS streams.

**Describe alternatives you've considered**
We can implement the steps from here ourselves. Or we can generate aws keypairs allowing for s3 buckets only.
https://docs.aws.amazon.com/iot/latest/developerguide/authorizing-direct-aws.html