Use terraform to config GCP proxy setup

With terraform (https://terraform.io) we can convert most of the infrastructure setup into code. This simplifies setting up a new proxy as well as providing reproducibility in the setup, eliminating human errors as much as possible.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=190634711

java/google/registry/proxy/terraform/modules/output.tf

@@ -0,0 +1,15 @@
+output "proxy_name_servers" {
+  value = "${google_dns_managed_zone.proxy_domain.name_servers}"
+}
+
+output "proxy_service_account_client_id" {
+  value = "${google_service_account.proxy_service_account.unique_id}"
+}
+
+output "proxy_ipv4_address" {
+  value = "${google_compute_global_address.proxy_ipv4_address.address}"
+}
+
+output "proxy_ipv6_address" {
+  value = "${google_compute_global_address.proxy_ipv6_address.address}"
+}