Setup k3s with the help of ansible after the infra-provisioning

This change is huge! It allows me to manage the k3s installation on the
hetzner-cloud I setup via terraform.

variables.tf

@@ -72,3 +72,8 @@ variable "k8s_agent_type" {
   type    = string
   default = "cax11"
 }
+
+variable "k3s_version" {
+  type        = string
+  description = "The k3s version to use."
+}