Support KMS encryption key rotation in Kafka buffer

[dlvenable]

Summary

The kafka buffer should support rotating the encryption_key. This is a high-level issue for supporting key rotation. Data Prepper is not doing any key rotation on KMS. Instead, it will support rotation of the encryption_key which is encrypted by a KMS key.

Tasks

• Include encrypted data key in Kafka buffer message. #3655
• Use the embedded encrypted_data_key to decrypt data when present
• Create Kafka buffer integration tests for KMS #3980
• Run KMS-related integration tests as part of the GitHub Actions #4040