feat: support IRSA and Pod Identities for Amazon Bedrock

[aaroniscode]

Closes #398

📑 Description

For Amazon Bedrock backend, add support for IAM Roles for Service Accounts (IRSA) and EKS Pod Identities

✅ Checks

• [X] My pull request adheres to the code style of this project
• [X] My code requires changes to the documentation
• [X] I have updated the documentation as required
• [X] All the tests have passed

ℹ Additional Information