UpCloud server plan, firewall, load balancer integration (#8758)

* [upcloud] add option to use preconfigured cpu/mem plan

* [upcloud] add option to use firewall rules for API server/SSH access

* [upcloud] add option to use managed load balancer

contrib/terraform/upcloud/output.tf

@@ -6,3 +6,7 @@ output "master_ip" {
 output "worker_ip" {
   value = module.kubernetes.worker_ip
 }
+
+output "loadbalancer_domain" {
+  value = module.kubernetes.loadbalancer_domain
+}