chore(ec2): NatInstanceProviderV2 security group example

[nmussy]

Issue # (if applicable)

Closes #27527

Reason for this change

The current NatInstanceProviderV2.securityGroup property is unusable, given the dependency loop between the construct props (NatInstanceProviderV2 > VPC > SecurityGroup > NatInstanceProviderV2).
When creating the integration for #29729, adding a getter for the instances generated by the provider to update the instance role was required to test the userData overload. This solution also allows to bypass the circular dependency describe above, given that both the VPC and the instances are generated once the VPC is created with the natGatewayProvider.

Description of changes

• Deprecate NatInstanceProviderV2.securityGroup
  • Add @example tag to demo NatInstanceProviderV2.gatewayInstances
• Update README to demo setting the security group
• Update integ to test the demo

Description of how you validated changes

Updated integration test

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[nmussy]

@arachnilith Can you confirm that this covers the feature request you raised in #27527?

[GavinZZ]

LGTM, thanks for making the change.

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

Pull request has been modified.

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 88c52e2
• Result: SUCCEEDED
• Build Logs (available for 30 days)

Powered by github-codebuild-logs, available on the AWS Serverless Application Repository

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[aws-cdk-automation]

Comments on closed issues and PRs are hard for our team to see. If you need help, please open a new issue that references this one.