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/versions.tf

@@ -0,0 +1,13 @@
+terraform {
+  required_providers {
+    tls = {
+      source = "hashicorp/tls"
+    }
+    hcloud = {
+      source = "hetznercloud/hcloud"
+    }
+    dns = {
+      source = "hashicorp/dns"
+    }
+  }
+}