Request for python version of AesKeyRing

## Problem

- Our producer is java based which uses [AesKeyRIng](https://github.com/aws/amazon-s3-encryption-client-java/blob/main/src/main/java/software/amazon/encryption/s3/materials/AesKeyring.java) with `S3EncryptionClient` to encrypt data.
- But our consumer side requiring to decrypt data is in Python. However, Python does not contain `AesKeyRing` equivalent.

We use AesKeyRing to generate DataKeys with our own WrappingKey generator , which is NOT KMS. This is a hard requirement for us and `AesKeyRing` unblocked us in java. However, we are blocked in python as its not available.

I wanted to raise this request to the team to implement a python version of `AesKeyRing` , so that we can be unblocked.

Start by reading the linked Java AesKeyring.java implementation and the S3EncryptionClient usage, then trace the Python package's existing encryption and keyring entry points. Done means a Python AesKeyRing equivalent can generate data keys with a caller-provided, non-KMS wrapping-key generator and decrypt data produced by the Java client.

Written by the indexing model from the issue text.