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/lib/testing/driver.nix

@@ -1,4 +1,9 @@
-{ config, lib, hostPkgs, ... }:
+{
+  config,
+  lib,
+  hostPkgs,
+  ...
+}:
 let
   inherit (lib) mkOption types literalMD;
 
@@ -11,10 +16,9 @@ let
     tesseract4 = hostPkgs.tesseract4.override { enableLanguages = [ "eng" ]; };
   };
 
-
-  vlans = map (m: (
-    m.virtualisation.vlans ++
-    (lib.mapAttrsToList (_: v: v.vlan) m.virtualisation.interfaces))) (lib.attrValues config.nodes);
+  vlans = map (
+    m: (m.virtualisation.vlans ++ (lib.mapAttrsToList (_: v: v.vlan) m.virtualisation.interfaces))
+  ) (lib.attrValues config.nodes);
   vms = map (m: m.system.build.vm) (lib.attrValues config.nodes);
 
   nodeHostNames =
@@ -23,13 +27,14 @@ let
     in
     nodesList ++ lib.optional (lib.length nodesList == 1 && !lib.elem "machine" nodesList) "machine";
 
-  pythonizeName = name:
+  pythonizeName =
+    name:
     let
       head = lib.substring 0 1 name;
       tail = lib.substring 1 (-1) name;
     in
-      (if builtins.match "[A-z_]" head == null then "_" else head) +
-      lib.stringAsChars (c: if builtins.match "[A-z0-9_]" c == null then "_" else c) tail;
+    (if builtins.match "[A-z_]" head == null then "_" else head)
+    + lib.stringAsChars (c: if builtins.match "[A-z0-9_]" c == null then "_" else c) tail;
 
   uniqueVlans = lib.unique (builtins.concatLists vlans);
   vlanNames = map (i: "vlan${toString i}: VLan;") uniqueVlans;
@@ -96,7 +101,12 @@ let
           --set testScript "$out/test-script" \
           --set globalTimeout "${toString config.globalTimeout}" \
           --set vlans '${toString vlans}' \
-          ${lib.escapeShellArgs (lib.concatMap (arg: ["--add-flags" arg]) config.extraDriverArgs)}
+          ${lib.escapeShellArgs (
+            lib.concatMap (arg: [
+              "--add-flags"
+              arg
+            ]) config.extraDriverArgs
+          )}
       '';
 
 in
@@ -165,7 +175,7 @@ in
         They become part of [{option}`driver`](#test-opt-driver) via `wrapProgram`.
       '';
       type = types.listOf types.str;
-      default = [];
+      default = [ ];
     };
 
     skipLint = mkOption {
@@ -191,8 +201,7 @@ in
     _module.args = {
       hostPkgs =
         # Comment is in nixos/modules/misc/nixpkgs.nix
-        lib.mkOverride lib.modules.defaultOverridePriority
-          config.hostPkgs.__splicedPackages;
+        lib.mkOverride lib.modules.defaultOverridePriority config.hostPkgs.__splicedPackages;
     };
 
     driver = withChecks driver;