Rename Windows warm/minimum IP targets

**What would you like to be enhanced**:
I would like to rename the Windows warm/minimum IP target variables that are read from the `amazon-vpc-cni` ConfigMap: https://github.com/aws/amazon-vpc-resource-controller-k8s/blob/master/pkg/config/type.go#L76

The current names cause confusion with the environment variables in the `aws-node` Daemonset that are used for warm/minimum targets on Linux nodes. I propose that we rename these to `windows-*`.

Since we cannot do the switchover all at once, I propose the VPC Resource Controller starts accepting both names, which will allow the AWS VPC CNI chart to change its names to the `windows-*` values.

**Why is the change needed and what use case will it solve**:
This change would help avoid customer confusion when it comes to deploying the AWS VPC CNI chart.