Allow Creation of Clusters in a user Controlled Subnet

[MadVikingGod]

Currently it is not possible to create an EKS Cluster outside of the 192.168.0.0/16 subnet.

Expected Resulsts
When defining a cluster a network and subnets can be specified. For example

network:
    vpcCider: "192.168.0.0/16"
    subnet1: "192.168.64.0/18"
    subnet2: "192.168.128.0/18"
    subnet3: "192.168.192.0/18"

And the cluster will be created with the correct subnets.

[anand99]

Is it ok to use following spec for network information:

    network:
      vpcCidr: 172.16.0.0/16
      subnetCidrs:
        - 172.16.0.0/24
        - 172.16.1.0/24
        - 172.16.2.0/24

Due to kubernetes-sigs/controller-tools#139 the fields with Digit in yaml spec not ending in CRD.

[anand99]

#62