Karpenter support for ROSA

1. Proposed title of this feature request

Karpenter support for ROSA

2. What is the nature and description of the request?
AWS's Karpenter project allows for intelligent scaling of an EKS dataplane with EC2 instances. Karpenter doesn't rely on node groups and instead uses Kubernetes to evaluate the workload requirements and choose from a pool of pre-defined, but varied EC2 options (size, billing type, arch, gpu, etc). This way it can choose right-sized collections of multiple instances. This can affect cost savings, scaling speed, and even overall environmental sustainability (by not over committing to many resources when not needed). Additionally, Karpenter can scale down to remove resources when not needed.

Karpenter is open source and works on a provider/plugin model.

https://karpenter.sh/

https://karpenter.sh/v0.26.1/contributing/

It's Kubernetes aware and built for K8s. 

Adding it to ROSA would allow ROSA customers to move away from the traditional model of having to add resources via groups of like-sized instances. They could create a Karpenter provisioner for their deployment that ensure the right instances are chosen and costs are better managed.

Ultimately, the plugin model means Karpenter can work with any cloud provider and could be used across GKE, Azure, and AWS allowing OCP uses the portability they expect from OCP and the cost savings and efficiency they expect from their cloud providers.

3. Why does the customer need this? (List the business requirements here)

• Allows customers to reduce AWS costs by provisioning from a mixed pool of EC2 instance types allowing the Karpenter to instruct the scheduler to pick the right sized instance based on need.
• This allows for cost savings
• This allows for a sustainability impact as if you only need a few CPUs you can pick a smaller one from the pool and not overprovision: environment wins!
• This is going to be standard on EKS control plans (see: https://github.com/aws/containers-roadmap/issues/1792) very soon 

4. List any affected packages or components.

• I don't know these.