Add initial Terraform module structure for firewall and network

- Created main.tf, output.tf, and variables.tf for the firewall module.
- Created main.tf, output.tf, and variables.tf for the network module.
- Added provider configuration for Hetzner Cloud and NetBox in provider.tf.
- Defined sensitive variables for Hetzner API token, NetBox URL, and NetBox API token in variables.tf.

terraform/variables.tf

@@ -0,0 +1,9 @@
+variable "hetzner_api_token" {
+  sensitive = true
+}
+variable "netbox_url" {
+  sensitive = true
+}
+variable "netbox_api_token" {
+  sensitive = true
+}