Warn about bad cluster configurations

There have been [some](https://github.com/k0sproject/k0s/issues/2888) [reports](https://forums.k8slens.dev/t/k0s-latest-release-is-killing-my-rpi4b-cpus/300) about high k0s resource consumption recently. Those reports were related to bad cluster configurations. What about adding some sort of warning into k0sctl once it detects such a configuration?

Things to warn about:
* No load balancer (i.e. neither `api.externalAddress` is set nor `network.nodeLocalLoadBalancing` is enabled) for clusters with more than one controller (#950)
* An even number of controllers when internal etcd is used
* Node-local load balancing is enabled, but [conflicts](https://docs.k0sproject.io/stable/nllb/#enabling-in-a-cluster) with other cluster settings.

Maybe also worth a warning, albeit there's no user report about it yet:
* More than one controller is configured when using kine+sqlite.