(aws-cloudfront-origins): Default Lambda Function URL Origins To Dual Stack IPv4/IPv6

### Describe the feature

[CloudFront recently launched support for IPv6 origins](https://aws.amazon.com/about-aws/whats-new/2025/09/amazon-cloudfront-ipv6-origins/).

[Lambda function URL's are by default dual stack](https://docs.aws.amazon.com/lambda/latest/dg/urls-configuration.html).

This feature request tracks automatically enabling dual stack support for Lambda function URL origins.

### Use Case

Right now, our Lambda function URL origins are using the (now legacy) IPv4 only configuration even though they support IPv6.

We would like to leverage IPv6 where possible.

### Proposed Solution

CloudFront has added [`IpAddressType ` in the `CustomOriginConfig `](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-cloudfront-distribution-customoriginconfig.html#cfn-cloudfront-distribution-customoriginconfig-ipaddresstype) in CloudFormation.

Given that, the update should be simply updating the rendering of the `CustomOriginConfig` [here](https://github.com/aws/aws-cdk/blob/v2.214.0/packages/aws-cdk-lib/aws-cloudfront-origins/lib/function-url-origin.ts#L73-L79).

### Other Information

_No response_

### Acknowledgements

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

### AWS CDK Library version (aws-cdk-lib)

n/a

### AWS CDK CLI version

n/a

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

n/a

Start with packages/aws-cdk-lib/aws-cloudfront-origins/lib/function-url-origin.ts, especially the CustomOriginConfig rendering linked in the issue. Check how the Lambda function URL origin is configured, then update the rendered configuration so it uses dual-stack IPv4/IPv6; done means CloudFormation receives the requested IpAddressType for this origin.

Written by the indexing model from the issue text.