Allow customized options for CCM

[Lykos153]

What feature would you like to be added?
I would like to be able to customize the deployment of the Cloud Controller Manager. Of course, I can do it manually, but I'd like to have it version controlled inside the manifest. Alternatively, add an option not to install the CCM at all, so users can install their own.

What are use cases of the feature?
The Hetzner CCM has some options for the load balancers, eg. HCLOUD_LOAD_BALANCERS_USE_PRIVATE_IP so the services don't have to be annotated individually.

[kron4eg]

With fresh alpha release we've refactored addons mechanisms and moved all CCMs that previously we've been shipping as go code to YAML addons. Here's hetzner CCM for example https://github.com/kubermatic/kubeone/tree/master/addons/ccm-hetzner.
Plus, we've made it so that it's possible to override our "internal" addons (like aforementioned CCMs) with custom. In case of hetzner all you need is to place ccm-hetzner directory (with your YAML) in configured addons directory.

All that will be released as kubeone v1.3, but for now I invite you to play with v1.3.0-alpha.0 pre-release, it's considered as stable.

[kron4eg]

I'll add HCLOUD_LOAD_BALANCERS_USE_PRIVATE_IP to our ccm-hetzner manifest.