implement ifwait trigger service and use in bridge

should we convert all ifwait uses to this trigger too? seems
reasonable

modules/ifwait/default.nix

@@ -0,0 +1,18 @@
+{ config, pkgs, lib, ... } :
+let
+  inherit (pkgs) liminix;
+  inherit (lib) mkOption types;
+in {
+  options.system.service.ifwait =
+    mkOption { type = liminix.lib.types.serviceDefn; };
+
+  config.system.service.ifwait = config.system.callService ./ifwait.nix {
+    state = mkOption { type = types.str; };
+    interface = mkOption {
+      type = liminix.lib.types.interface;
+    };
+    service = mkOption {
+      type = liminix.lib.types.service;
+    };
+  };
+}

modules/ifwait/ifwait.nix

@@ -0,0 +1,15 @@
+{ ifwait, liminix } :
+{
+  state
+, interface
+, service
+}:
+let
+  inherit (liminix.services) longrun;
+in longrun {
+  name = "ifwait.${interface.name}";
+  buildInputs = [ service ];
+  run = ''
+    ${ifwait}/bin/ifwait -s ${service.name}  $(output ${interface} ifname) ${state}
+  '';
+}