feat(elasticloadbalancingv2): add support for multi-value headers in Lambda target groups (#34298)

### Issue # (if applicable)

None

### Reason for this change

We can set a multi-value headers property for a lambda target group from cloudformation, but this was not supported in the AWS CDK L2 construct.

### Description of changes

Add multiValueHeadersEnabled property to ApplicationTargetGroupProps and set it in the ApplicationTargetGroup constructor.

### Describe any new or updated permissions being added

None

### Description of how you validated changes

Added both unit and integration 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: kawabata-mcl