aws_cdk.aws_rds.CfnIntegration: L2 construct including additional steps

### Describe the feature

Currently, the aws_cdk.aws_rds.CfnIntegration resource can set up a Zero-ETL integration, but there are additional, manual steps required. Those steps are:
- Set an authorized principal
- Set an authorized integration source
- Create the target database that will receive the synchronized data

To address this, I propose adding an L2 construct that handles those steps together with the Zero-ETL integration itself.

### Use Case

At the moment we have to set the authorized principal, authorized integration source, then we setup the integration with aws_cdk.aws_rds.CfnIntegration and finally we have to create the target database.
This could be simplified with a new construct combining those steps. This would ensure simplified deployment, reduced complexity and lower risk of errors.

### Proposed Solution

_No response_

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### CDK version used

2.174.1

### Environment details (OS name and version, etc.)

macOS Sequoia 15.2

Start by reviewing the existing aws_rds.CfnIntegration resource and how the three manual authorization and target-database steps are represented in the AWS CDK. Done means a proposed L2 construct can combine those steps with the Zero-ETL integration, but the issue does not identify files, tests, or a detailed proposed API.

Written by the indexing model from the issue text.