[AWS::EKS::Cluster] - add GetAtt for KubernetesNetworkConfig.ServiceIpv4Cidr

### Name of the resource

AWS::EKS::Cluster

### Resource name

_No response_

### Description

Cloudformation currently supports only `KubernetesNetworkConfig.ServiceIpv6Cidr` using GetAtt Intrinsic Function per this [document](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-eks-cluster.html#aws-resource-eks-cluster-return-values). Support for `KubernetesNetworkConfig.ServiceIpv4Cidr` is missing.

Request:
* add `KubernetesNetworkConfig.ServiceIpv4Cidr` support to retrieve selected ServiceIpv4Cidr

### Other Details

Why this is needed:
For those EKS Clusters where [ServiceIpv4Cidr](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-eks-cluster-kubernetesnetworkconfig.html#cfn-eks-cluster-kubernetesnetworkconfig-serviceipv4cidr) is not explicitly defined, Kubernetes will automatically assigns a suitable CIDR block. However, this CIDR block [is now needed](https://docs.aws.amazon.com/eks/latest/userguide/eks-optimized-ami.html#al2023) for new AmazonLinux2023 self-managed node groups. For automation purposes where cluster and nodegroups are defined and deployed in a single pass (like: cdk synth/deploy) we need this (unknown in advance) CIDR block information to be available between resources and stacks.

Start with the AWS::EKS::Cluster CloudFormation return values and the existing KubernetesNetworkConfig.ServiceIpv6Cidr GetAtt support. Add the corresponding ServiceIpv4Cidr retrieval, then verify that an automatically assigned service CIDR can be exposed for use by dependent resources and stacks.

Written by the indexing model from the issue text.