Provide helper methods to use `boto3` instead of the `minio` client

**Is your feature request related to a problem? Please describe.**
While working on an `AWS` project using this stack, we realised that we have to use `boto3` for various things like accessing the `SecretsManager` and objects in `s3` when the environment exchanges credentials using `IAM` policies (where the application itself does not need the keys to access the bucket).

It would be nice to provide a `boto3` wrapped up to work with this stack.

**Describe the solution you'd like**
A set of wrapper methods on the `s3_file_metadata` table that allow us to work with `IAM` managed `s3` buckets. These can be specifically be prefixed with `aws_` to indicate that they work in an AWS managed environment only.

Secondly consider best practices around working with multiple buckets, in our use case we use a bucket to provide `media` files (accessed via a CDN) and the the other has user generated content which are only to be accessed via signed urls.

As for documentation it will be helpful to provide assumptions and samples.

**Describe alternatives you've considered**
NA

**Additional context**
See [aws-eks-cluster](https://github.com/anomaly/aws-eks-cluster) for a `terraform` deployed AWS environment which is setup in the way described above.