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/services/web-servers/nginx/location-options.nix

@@ -11,7 +11,7 @@ with lib;
   options = {
     basicAuth = mkOption {
       type = types.attrsOf types.str;
-      default = {};
+      default = { };
       example = literalExpression ''
         {
           user = "password";
@@ -100,7 +100,12 @@ with lib;
     };
 
     return = mkOption {
-      type = with types; nullOr (oneOf [ str int ]);
+      type =
+        with types;
+        nullOr (oneOf [
+          str
+          int
+        ]);
       default = null;
       example = "301 http://example.com$request_uri";
       description = ''
@@ -110,7 +115,7 @@ with lib;
 
     fastcgiParams = mkOption {
       type = types.attrsOf (types.either types.str types.path);
-      default = {};
+      default = { };
       description = ''
         FastCGI parameters to override.  Unlike in the Nginx
         configuration file, overriding only some default parameters