aws-eks-v2: AccessEntry does not expose KubernetesGroups

### Describe the bug

Using `grantAccess()` and `new eks.AccessEntry()` does not provide the ability to specify `kubernetesGroups` as part of the access entry.

### Regression Issue

- [ ] Select this option if this issue appears to be a regression.

### Last Known Working CDK Library Version

_No response_

### Expected Behavior

`kubernetesGroups` is exposed in both approaches.

### Current Behavior

The property is missing.

### Reproduction Steps

The properties are just missing.

### Possible Solution

_No response_

### Additional Information/Context

_No response_

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

2.248.0

### AWS CDK CLI version

2.1106

### Node.js Version

24

### OS

darwin

### Language

TypeScript

### Language Version

_No response_

### Other information

_No response_

Start with the grantAccess() and eks.AccessEntry() entry points and inspect how their properties are defined and tested. Confirm that kubernetesGroups can be specified through both approaches, then verify the relevant EKS tests cover the exposed property.

Written by the indexing model from the issue text.