Support for RKE2 and K3S

This adds support for K3S and RKE2 clusters. It is not possible to just switch from one to the other, you will need to rebuild the cluster.

RKE1 is deprecated and will stop to be supported on July 31st, 2025. If you want to use either RKE2 or K3S you will need to change the network_plugin.

terraform/modules/cluster/key.tf

 # Each cluster will either have a shared key, or their own
 # unique key.
 resource "openstack_compute_keypair_v2" "key" {
-  #count      = 1 #var.openstack_ssh_key == "" ? 0 : 1
+  count      = var.openstack_ssh_key == "" ? 1 : 0
   name = var.cluster_name
 }
 
+data "openstack_compute_keypair_v2" "key" {
+  count = var.openstack_ssh_key == "" ? 0 : 1
+  name  = var.openstack_ssh_key
+}
+
 # set local variable to hold final key, either created or
 # loaded.
 locals {
-  key = var.cluster_name # var.openstack_ssh_key == "" ? var.cluster_name : var.openstack_ssh_key
+  key_name = var.openstack_ssh_key == "" ? openstack_compute_keypair_v2.key[0].name : data.openstack_compute_keypair_v2.key[0].name
+  private_key = var.openstack_ssh_key == "" ? openstack_compute_keypair_v2.key[0].private_key : ""
 }