[v1beta2] Consider implementing a new `spec.machineTemplate.readinessGates` field

[furkatgofurov7]

Describe the solution you'd like:
CAPI v1.10 migration book suggests by contract that control plane providers which allow definition of machine readiness gates SHOULD implement the following machineTemplate field: spec.machineTemplate.readinessGates

Why do you want this feature:
To align with CAPI contract and meet control plane providers requirements

Anything else you would like to add:
More info: https://cluster-api.sigs.k8s.io/developer/providers/contracts/control-plane#controlplane-machines & https://cluster-api.sigs.k8s.io/developer/providers/migrations/v1.9-to-v1.10#suggested-changes-for-providers