Move user definition from options.nix to args.nix

This is intended to make this more consistent with other examples
in this repo.

Author: thalin

modules/geth/args.nix

@@ -174,6 +174,12 @@ with lib; {
     description = "Maximum peers to connect to.";
   };
 
+  user = mkOption {
+    type = types.nullOr types.str;
+    default = null;
+    description = "User to run the service as.";
+  };
+
   datadir = mkOption {
     type = types.nullOr types.str;
     default = null;

modules/geth/options.nix

@@ -9,12 +9,6 @@
     options = rec {
       enable = mkEnableOption "Go Ethereum Node";
 
-      user = mkOption {
-        type = types.nullOr types.str;
-        default = null;
-        description = "User to run the service as.";
-      };
-
       inherit args;
 
       extraArgs = mkOption {