Add support for AWS IAM login

[piochelepiotr]

What does this PR do?

Adds support for AWS MSK IAM authentication to the Kafka Consumer integration using SASL/OAUTHBEARER mechanism.

Motivation

Customers using Amazon MSK clusters with IAM authentication were unable to monitor their Kafka infrastructure with the Datadog Agent. Previously, they had to use SASL/SCRAM or mTLS authentication, which requires manual credential management.

This change enables monitoring AWS MSK clusters using IAM roles, providing:

• No credential management (uses AWS IAM roles automatically)
• Fine-grained access control via IAM policies
• Automatic token rotation

Configuration:
instances:

• kafka_connect_str: "broker:9098"
  security_protocol: SASL_SSL
  sasl_mechanism: OAUTHBEARER
  sasl_oauth_token_provider:
  method: aws_msk_iamImplementation:
• Uses aws-msk-iam-sasl-signer-python to generate AWS IAM tokens
• OAuth callback provides tokens to confluent-kafka client
• Fully backwards compatible with existing OIDC configurations
• Tested end-to-end on real AWS MSK cluster

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[codecov]

Codecov Report

❌ Patch coverage is 74.13793% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.02%. Comparing base (8c6c226) to head (d51d7a5).
⚠️ Report is 13 commits behind head on master.

Additional details and impacted files

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[chnn]

Could this be validated in config.py somehow instead? Defaulting to us-east-1 seems like it could cause subtle failures that are a headache to debug