Enable custom nodeSelector for built-in components

[rmannibucau]

Is your feature request related to a problem? Please describe.

nodeSelector is hardcoded for most components (think metrics-server for ex).
It does not enable to customize the node (or pool) you want it to be deployed to.

Describe the solution you would like

Have a variable in k0s.yml/k0sctl.yaml to do it.

Describe alternatives you've considered

Manual edit but it is not very robust.

Additional context

No response

[jnummelin]

And I assume we'd need to add it in a way that there's nodeSelector separately for each component, right? I don't think it can work properly with only single nodeSelector that would cover all components

[rmannibucau]

Ideally yes 🙏