Update resman modules (#475)

* Make logging sinks in different resources use the same API

* Split resman modules in multiple files. Add nullables where applicable

modules/project/main.tf

@@ -89,7 +89,7 @@ resource "google_essential_contacts_contact" "contact" {
 
 resource "google_monitoring_monitored_project" "primary" {
   provider      = google-beta
-  for_each      = toset(coalesce(var.metric_scopes, []))
+  for_each      = toset(var.metric_scopes)
   metrics_scope = each.value
   name          = local.project.project_id
 }