feat(rds): support for local write forwarding in an Aurora Mysql cluster (#31524)

### Issue # (if applicable)

Closes #31523 .

### Reason for this change

Cloudformation supports [enabling local write forwarding](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbcluster.html#cfn-rds-dbcluster-enablelocalwriteforwarding) feature but AWS CDK does not support it.

### Description of changes

- Add `enableLocalWriteForwarding` to `DatabaseClusterBaseProps`
- Add validation that `engineType` is either `aurora` or `aurora-mysql`
  - Having `engineType` set to `aurora` means launching a MySQL-compatible Aurora cluster.

### Description of how you validated changes

Add both unit and integ tests.

### 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: badmintoncryer