Add hot reload test tasks for Linux and Windows desktop (#73889)

dev/devicelab/bin/tasks/hot_mode_dev_cycle_linux_target__benchmark.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_devicelab/tasks/hot_mode_tests.dart';
+import 'package:flutter_devicelab/framework/framework.dart';
+
+Future<void> main() async {
+  await task(createHotModeTest(deviceIdOverride: 'linux'));
+}

dev/devicelab/bin/tasks/hot_mode_dev_cycle_win_target__benchmark.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_devicelab/tasks/hot_mode_tests.dart';
+import 'package:flutter_devicelab/framework/framework.dart';
+
+Future<void> main() async {
+  await task(createHotModeTest(deviceIdOverride: 'windows'));
+}