treewide: Format all Nix files

Format all Nix files using the officially approved formatter,
making the CI check introduced in the previous commit succeed:

  nix-build ci -A fmt.check

This is the next step of the of the [implementation](https://github.com/NixOS/nixfmt/issues/153)
of the accepted [RFC 166](https://github.com/NixOS/rfcs/pull/166).

This commit will lead to merge conflicts for a number of PRs,
up to an estimated ~1100 (~33%) among the PRs with activity in the past 2
months, but that should be lower than what it would be without the previous
[partial treewide format](https://github.com/NixOS/nixpkgs/pull/322537).

Merge conflicts caused by this commit can now automatically be resolved while rebasing using the
[auto-rebase script](8616af08d9/maintainers/scripts/auto-rebase).

If you run into any problems regarding any of this, please reach out to the
[formatting team](https://nixos.org/community/teams/formatting/) by
pinging @NixOS/nix-formatting.

nixos/modules/security/rtkit.nix

@@ -1,7 +1,13 @@
 # A module for ‘rtkit’, a DBus system service that hands out realtime
 # scheduling priority to processes that ask for it.
 
-{ config, lib, pkgs, utils, ... }:
+{
+  config,
+  lib,
+  pkgs,
+  utils,
+  ...
+}:
 
 with lib;
 
@@ -9,7 +15,8 @@ let
   cfg = config.security.rtkit;
   package = pkgs.rtkit;
 
-in {
+in
+{
 
   options = {
 
@@ -26,7 +33,7 @@ in {
 
     security.rtkit.args = mkOption {
       type = types.listOf types.str;
-      default = [];
+      default = [ ];
       description = ''
         Command-line options for `rtkit-daemon`.
       '';
@@ -38,7 +45,6 @@ in {
 
   };
 
-
   config = mkIf cfg.enable {
 
     security.polkit.enable = true;
@@ -52,18 +58,17 @@ in {
 
     systemd.services.rtkit-daemon = {
       serviceConfig.ExecStart = [
-        ""  # Resets command from upstream unit.
+        "" # Resets command from upstream unit.
         "${package}/libexec/rtkit-daemon ${utils.escapeSystemdExecArgs cfg.args}"
       ];
     };
 
-    users.users.rtkit =
-      {
-        isSystemUser = true;
-        group = "rtkit";
-        description = "RealtimeKit daemon";
-      };
-    users.groups.rtkit = {};
+    users.users.rtkit = {
+      isSystemUser = true;
+      group = "rtkit";
+      description = "RealtimeKit daemon";
+    };
+    users.groups.rtkit = { };
 
   };