feat: Include all Provider fields in the AWSNodeTemplate CRD

[suket22]

Description
As part of releasing custom UserData support, this moves all of the provider fields into ProviderRef as well. This should allow everyone to specify everything related to the AWS provider within the AWSNodeTemplate CRD.

Made a couple more changes while I was on this -

• Got rid of ProviderRefNamespace - dunno why I did this given the CRD was cluster scoped anyway.
• Fixed the CRD. I had set paths to awsnodetemplate which is the annotation kubebuilder is looking for to determine the plural name of the CRD. Anyone running a pre-release version of Karpenter should be unaffected as long as they update the charts. (new CRD works, and old provisioner yaml is fine).

How was this change tested?
Tested a few things on this front -

• Made sure that the validation webhook is working on the Provider fields inside the AWSNodeTemplate CRD.
• Made sure you can't specify provider and providerRef.
• Validated that old behavior works (spinning up AL2 and Bottlerocket nodes)
• Validated that new behavior works (spinning up AL2 and Bottlerocket nodes with UserData using the new CRD).

Example Manifest to try this change out -

apiVersion: karpenter.sh/v1alpha5
kind: Provisioner
metadata:
  name: default
spec:
  limits:
    resources:
      cpu: 20
  providerRef:
    name: default
  ttlSecondsAfterEmpty: 30
---
apiVersion: karpenter.k8s.aws/v1alpha1
kind: AWSNodeTemplate
metadata:
  name: default
spec:
  amiFamily: Bottlerocket
  instanceProfile: KarpenterNodeInstanceProfile-karp-cluster
  subnetSelector:
    karpenter.sh/discovery: karp-cluster
  securityGroupSelector:
    karpenter.sh/discovery: karp-cluster
  userData:  |
    [settings.kubernetes]
    kube-api-qps = 30

Does this change impact docs?
Docs will be added in a subsequent PR since this change is large enough as-is.
I'll need to add -

1. Some examples on CRD and Provisioner Usage.
2. Undo the changes that hide the user data documentation.
3. Additions to the upgrade guide.

With that, a separate PR makes sense.

• Yes, PR includes docs updates
• Yes, issue opened: #
• No

Release Note

feat: Include all Provider fields in the AWSNodeTemplate CRD

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

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