feat(rds): support auto-pause configuration for Aurora Serverless v2 (#34173)

### Issue # (if applicable)

Closes #32280.
Closes #32563.

### Reason for this change

Aurora Serverless v2 DB instances can specify the time period of inactivity before auto-pause.
https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-serverless-v2-auto-pause.html

### Description of changes

Added the `serverlessV2AutoPauseDuration` prop for `DatabaseCluster`.

### Describe any new or updated permissions being added

N/A

### Description of how you validated changes

Added unit tests and an integ test.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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

Author: Tietew