Terraform support for UpCloud (#7360)

* terraform support for UpCloud

* terraform support for UpCloud

* terraform support for UpCloud

* terraform support for UpCloud

* terraform support for UpCloud

* terraform support for UpCloud

* terraform support for UpCloud

* Updates to README.md and main.tf files

* formatting and updating readme

* added a .terraform_validate CI job

* fixed format issue

* added sample inventory

* added symbolic link to group_vars

* added missing tf variables and minor fixes

* added text formatting

* minor formatting fixes

contrib/terraform/upcloud/variables.tf

@@ -0,0 +1,35 @@
+
+variable "zone" {
+  description = "The zone where to run the cluster"
+}
+
+variable "hostname" {
+  default = "example.com"
+}
+
+variable "template_name" {}
+
+variable "username" {}
+
+variable "machines" {
+  description = "Cluster machines"
+  type = map(object({
+    node_type = string
+    cpu       = string
+    mem       = string
+    disk_size = number
+  }))
+}
+
+variable "ssh_public_keys" {
+  description = "List of public SSH keys which are injected into the VMs."
+  type        = list(string)
+}
+
+variable "inventory_file" {
+  description = "Where to store the generated inventory file"
+}
+
+variable "UPCLOUD_USERNAME" {}
+
+variable "UPCLOUD_PASSWORD" {}