need for RKE2ControlPlane status.version field to support MachineSetPreflightChecks

[tmmorin]

Describe the solution you'd like:

In the context of Sylva project, we need to use MachineSetPreflightChecks and RKE2ControlPlane is missing a status.version to satisfy the Cluster API contract needed to use MachineSetPreflightChecks.

https://cluster-api.sigs.k8s.io/tasks/experimental-features/machineset-preflight-checks

Why do you want this feature:

MachineSetPreflightChecks are needed to ensure that we can satisfy Kubernetes version skew constraints while upgrading a cluster (upgrading the control plane before MachineDeployments).

Details:

• https://github.com/kubernetes-sigs/cluster-api/blob/c3ae478440996666f015288367b59d802fd50d92/internal/controllers/machineset/machineset_preflight.go#L150

• https://github.com/kubernetes-sigs/cluster-api/blob/c3ae478440996666f015288367b59d802fd50d92/internal/contract/controlplane.go#L175

// IsUpgrading returns true if the control plane is in the middle of an upgrade, false otherwise.
// A control plane is considered upgrading if:
// - if spec.version is greater than status.version.

• https://github.com/kubernetes-sigs/cluster-api/blob/c3ae478440996666f015288367b59d802fd50d92/internal/contract/controlplane.go#L153

	// We can know if the control plane was previously created or is being cretaed for the first
	// time by looking at controlplane.status.version. If the version in status is set to a valid
	// value then the control plane was already provisioned at a previous time. If not, we can
	// assume that the control plane is being created for the first time.

References

Sylva issue https://gitlab.com/sylva-projects/sylva-core/-/issues/1658