HyperShift CEL validation blocks ARM64 NodePool creation for non-AWS/Azure platforms
Can't add a Bare Metal worker node to the hosted cluster. 
This was discussed on #project-hypershift Slack channel.

MultiClusterEngine v2.7.2 
HyperShift Operator image: 
registry.redhat.io/multicluster-engine/hypershift-rhel9-operator@sha256:56bd0210fa2a6b9494697dc7e2322952cd3d1500abc9f1f0bbf49964005a7c3a   

Always

1. Create a HyperShift HostedCluster on a non-AWS/non-Azure platform
2. Try to create a NodePool with ARM64 architecture specification

- CEL validation blocks creating NodePool with arch: arm64 on non-AWS/Azure platforms
- Receive error: "The NodePool is invalid: spec: Invalid value: "object": Setting Arch to arm64 is only supported for AWS and Azure"
- Additional validation in NodePool spec also blocks arm64 architecture

- Allow ARM64 architecture specification for NodePools on BareMetal platform 
- Remove or update the CEL validation to support this use case

NodePool YAML:
apiVersion: hypershift.openshift.io/v1beta1
kind: NodePool
metadata:
  name: nodepool-doca5-1
  namespace: doca5
spec:
  arch: arm64
  clusterName: doca5
  management:
    autoRepair: false
    replace:
      rollingUpdate:
        maxSurge: 1
        maxUnavailable: 0
      strategy: RollingUpdate
    upgradeType: InPlace
  platform:
    agent:
      agentLabelSelector: {}
    type: Agent
  release:
    image: quay.io/openshift-release-dev/ocp-release:4.16.21-multi
  replicas: 1