coturn: add systemd support (#394670)

nixos/modules/services/networking/coturn.nix

···
               chmod 640 ${runConfig}
             '';
             serviceConfig = rec {
-              Type = "simple";
+              Type = "notify";
               ExecStart = utils.escapeSystemdExecArgs [
                 (lib.getExe' pkgs.coturn "turnserver")
                 "-c"
···
                 [
                   "AF_INET"
                   "AF_INET6"
+                  "AF_UNIX"
                 ]
                 ++ lib.optionals (cfg.listening-ips == [ ]) [
                   # only used for interface discovery when no listening ips are configured

pkgs/by-name/co/coturn/package.nix

···
   libmicrohttpd,
   sqlite,
   nixosTests,
+  systemdMinimal,
 }:
 
 stdenv.mkDerivation rec {
···
     pkg-config
   ];
 
-  buildInputs = [
-    openssl
-    (libevent.override { inherit openssl; })
-    libprom
-    libmicrohttpd
-    sqlite.dev
-  ];
+  buildInputs =
+    [
+      openssl
+      (libevent.override { inherit openssl; })
+      libprom
+      libmicrohttpd
+      sqlite.dev
+    ]
+    ++ lib.optionals (lib.meta.availableOn stdenv.hostPlatform systemdMinimal) [
+      systemdMinimal
+    ];
 
   patches = [
     ./pure-configure.patch