Support multiple worker node groups.

[bnrjee]

What would you like to be added:
Add support for multiple worker node groups.
Why is this needed:
This feature is needed for users to create worker nodes with different configurations. It will also help to implement taints support fully on eks-anywhere clusters. Without multiple worker node groups NoExecute and NoSchedule taints can not be added on worker nodes. These taints prevent eks-anywhere specific deployments as these deployments generally don't have toleration.

Below are the tasks that are needed to be completed for this feature.

• Design doc Design doc for multiple worker node groups support #757
• Formation and parsing of cluster spec Support multiple worker node groups during vSphere cluster creation #968
• Adding worker node groups during upgrade #1012
• Add support to remove worker node groups during cluster upgrade #1054
• Add validator tests using multiple worker node groups
• doc update Update docs for multiple worker node groups & resolvConf #1040
• e2e tests