BIG changes. Make almost every server service modular, to distribute among multiple servers

modules/system/services/server/nginx/user/default.nix

@@ -0,0 +1,15 @@
+{ config, lib, ... }:
+{
+  users = lib.mkIf config.services.nginx.enable {
+    users.nginx = {
+      group = "nginx";
+      extraGroups = [
+        "turnserver"
+        "virtualMail"
+      ];
+      isSystemUser = true;
+      uid = 60;
+    };
+    groups.nginx = {};
+  };
+}