Add validation to check BMC connectivity earlier in cluster creation

[pokearu]

Description

Currently if there is a problem with connecting with the node's BMC during Bare-metal EKS-A cluster create, users have to look at the BaseboardManagement object .Status.Conditions to know if there is an error. This happens very late in the cluster create flow, when waiting for the control plane.

Possible fix

Adding a mid-flight validation to have a kubectl wait <BaseboardManagement> for=condition=Contactable earlier in the cluster create workflow.