Kubeconfig file generation for EKS

**Expected Behavior**

AWS Tools for Powershell should have a Cmdlet equivalent of https://docs.aws.amazon.com/cli/latest/reference/eks/update-kubeconfig.html

**Current Behavior**

AWS Tools for Powershell currently does not support generation of a kubeconfig file for an EKS cluster.

**Context**
Some customers cannot use the CLI due to technical or policy limitations. With a PowerShell alternative not being available, these customers have to manually create these files to connect to their EKS clusters.

Start by reviewing the AWS CLI update-kubeconfig reference linked in the issue and the EKS and PowerShell cmdlet entry points in this repository. Define the equivalent cmdlet's required inputs and behavior, then verify that it generates a kubeconfig file that connects to an EKS cluster.

Written by the indexing model from the issue text.