nixosTests.avahi: add avahi-with-resolved

This allows testing avahi works with resolved being enabled, as a
regression test for https://github.com/NixOS/nixpkgs/pull/99530.

nixos/tests/all-tests.nix

@@ -26,6 +26,7 @@ in
   agda = handleTest ./agda.nix {};
   atd = handleTest ./atd.nix {};
   avahi = handleTest ./avahi.nix {};
+  avahi-with-resolved = handleTest ./avahi.nix { networkd = true; };
   babeld = handleTest ./babeld.nix {};
   bazarr = handleTest ./bazarr.nix {};
   bcachefs = handleTestOn ["x86_64-linux"] ./bcachefs.nix {}; # linux-4.18.2018.10.12 is unsupported on aarch64

nixos/tests/avahi.nix

@@ -1,5 +1,11 @@
+{ system ? builtins.currentSystem
+, config ? {}
+, pkgs ? import ../.. { inherit system config; }
+# bool: whether to use networkd in the tests
+, networkd ? false }:
+
 # Test whether `avahi-daemon' and `libnss-mdns' work as expected.
-import ./make-test-python.nix ({ pkgs, ... } : {
+import ./make-test-python.nix ({ ... } : {
   name = "avahi";
   meta = with pkgs.stdenv.lib.maintainers; {
     maintainers = [ eelco ];
@@ -17,6 +23,11 @@ import ./make-test-python.nix ({ pkgs, ... } : {
         publish.workstation = true;
         extraServiceFiles.ssh = "${pkgs.avahi}/etc/avahi/services/ssh.service";
       };
+    } // pkgs.lib.optionalAttrs (networkd) {
+      networking = {
+        useNetworkd = true;
+        useDHCP = false;
+      };
     };
   in {
     one = cfg;