Move GCP proxy code to the old [] proxy's location

1. Moved code for the GCP proxy to where the [] proxy code used to live.
3. Corrected reference to the GCP proxy location.
4. Misc changes to make ErrorProne and various tools happy.

+diekmann to LGTM terraform whitelist change.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=213630560

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

@@ -0,0 +1,21 @@
+resource "google_dns_managed_zone" "proxy_domain" {
+  name     = "proxy-domain"
+  dns_name = "${var.proxy_domain_name}."
+}
+
+module "proxy_networking" {
+  source                = "./networking"
+  proxy_instance_groups = "${local.proxy_instance_groups}"
+  proxy_ports           = "${var.proxy_ports}"
+  proxy_domain          = "${google_dns_managed_zone.proxy_domain.name}"
+  proxy_domain_name     = "${google_dns_managed_zone.proxy_domain.dns_name}"
+}
+
+module "proxy_networking_canary" {
+  source                = "./networking"
+  proxy_instance_groups = "${local.proxy_instance_groups}"
+  suffix                = "-canary"
+  proxy_ports           = "${var.proxy_ports_canary}"
+  proxy_domain          = "${google_dns_managed_zone.proxy_domain.name}"
+  proxy_domain_name     = "${google_dns_managed_zone.proxy_domain.dns_name}"
+}