Add host_resolver.mojom and update network_service.mojom

mojo/services/network/public/interfaces/host_resolver.mojom

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module mojo;
+
+import "mojo/public/interfaces/network/network_error.mojom";
+import "network/public/interfaces/net_address.mojom";
+
+interface HostResolver {
+  // Get the list of IP addresses for host.
+  GetHostAddresses(string host, NetAddressFamily family) =>
+      (NetworkError result, array<NetAddress>? addresses);
+};