feat: Add terraform config for review-app[1]

Also removed the logic for deploying to the long gone aur-dev box.

Ansible will be added in a upcoming commit for configurating and
deploying aurweb on the VM.

[1] https://docs.gitlab.com/ee/ci/review_apps/

ci/tf/variables.tf

@@ -0,0 +1,36 @@
+variable "hcloud_token" {
+  type      = string
+  sensitive = true
+}
+
+variable "dns_server" {
+  type = string
+}
+
+variable "dns_tsig_key" {
+  type = string
+}
+
+variable "dns_tsig_algorithm" {
+  type = string
+}
+
+variable "dns_tsig_secret" {
+  type = string
+}
+
+variable "dns_zone" {
+  type = string
+}
+
+variable "name" {
+  type = string
+}
+
+variable "server_type" {
+  type = string
+}
+
+variable "datacenter" {
+  type = string
+}