refactor(postgres): Split postgres module

configuration/services/nextcloud.nix

@@ -103,6 +103,17 @@ in
     };
   };
 
+  services.postgresql = {
+    ensureUsers = [
+      {
+        name = "nextcloud";
+        ensureDBOwnership = true;
+      }
+    ];
+
+    ensureDatabases = [ "nextcloud" ];
+  };
+
   # Ensure that this service doesn't start before postgres is ready
   systemd.services.nextcloud-setup.after = [ "postgresql.target" ];