Provide option to enable autoscaler

[anbraten]

Maybe it would be possible to add the Hetzner autoscaler: https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/cloudprovider/hetzner/README.md

I will check if I can create a PR for it if it will be welcome.

[toabi]

If it adds separate pools of nodes which are not defined with terraform but they behave (roughly) the same (e.g. labels) why not.

I think the necessary things we already define somewhere else and could be used to create the necessary autoscaler resources.

I'd like it.

[gc-ss]

I will check if I can create a PR for it if it will be welcome.

Having a Hetzner autoscaler would be awesome!