Add cloud provider for Rancher with RKE2

[ctrox]

Which component this PR applies to?

cluster-autoscaler

What type of PR is this?

/kind feature

What this PR does / why we need it:

Adds cluster-autoscaler provider for Rancher with RKE2. This has been tried before but as this was for RKE (1) clusters, it works in a completely different way as Rancher fully changed their APIs and provisioning for RKE2. This provider only supports RKE2, which is now GA as of Rancher v2.6.5.

Special notes for your reviewer:

RKE2 provisioning uses cluster-api under the hood, so there are some similarities to the cluster-api provider but not enough to be able to share code. Plus I assume that is probably not really desired anyway. Since the Rancher server manages the cluster-api objects, it's not possible to simply run the cluster-api autoscaler as these two controllers would fight over control, plus changes would not be reflected in the corresponding Rancher API objects.

Not super sure about the proper process of the OWNERS file, but I saw in a recent PR that added a cloud provider that it was requested that there's a OWNERS file with the gitub handles commented out, so I added that. All the owners I added are members of @ninech and we are committed to maintaining this but of course would be more than happy if anybody else wants to help maintain this (e.g Rancher themselves or Ubisoft which was working on the old PR).

Does this PR introduce a user-facing change?

yes

Adds support for Rancher with RKE2 in cluster-autoscaler

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

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[ctrox]

/assign @towca

[mwielgus]

Please rebase and we are good to go.

[ctrox]

Please rebase and we are good to go.

Done, thank you!

[mwielgus]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ctrox, mwielgus

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• cluster-autoscaler/OWNERS [mwielgus]

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