Create feature support matrix

[mattfenwick]

Including:

underlying OS:

• linux
• windows

kube version:

• 1.21
• 1.20
• 1.19

IP stack:

• IPV4
• dual-stack
• IPV6

CNI:

• Antrea
• Calico
• Cilium
• ovn-kubernetes
• flannel
• weave

Cluster:

• kind
• k3s
• GKE
• AKS
• EKS
• bare-metal

What else?