kubeadm

* feat: add user facing variable with default

* feat: remove rolebinding to anonymous users after init and upgrade

* feat: use file discovery for secondary control plane nodes

* feat: use file discovery for nodes

* fix: do not fail if rolebinding does not exist

* docs: add warning about kube_api_anonymous_auth

* style: improve readability of delegate_to parameter

* refactor: rename discovery kubeconfig file

* test: enable new variable in hardening and upgrade test cases

* docs: add option to config parameters

* test: multiple instances and upgrade