Add a script to serve a local DevTools build

Change-Id: I499b45830bacf8899c5db8d776f7a6c3a47e53b4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/231362
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Kenzie (Schmoll) Davisson <kenzieschmoll@google.com>

pkg/dds/tool/devtools_server/serve_local.dart

@@ -0,0 +1,33 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:args/args.dart';
+import 'package:dds/devtools_server.dart';
+
+const argDevToolsBuild = 'devtools-build';
+
+void main(List<String> args) {
+  final argParser = ArgParser()
+    ..addOption(
+      argDevToolsBuild,
+      help: 'The location of the DevTools build to serve from DevTools server '
+          '(e.g. --devtools-build=absolute/path/to/devtools/build).',
+      mandatory: true,
+    );
+
+  try {
+    final ArgResults argResults = argParser.parse(args);
+    unawaited(
+      DevToolsServer().serveDevTools(
+        customDevToolsPath: argResults[argDevToolsBuild],
+      ),
+    );
+  } on FormatException catch (e) {
+    print(e.message);
+    print('');
+    print(argParser.usage);
+  }
+}