Added Hardcore Warning Widget

This widget will be used in several places to notify the player that a feature has been disabled because hardcore mode is on. It includes a button to open the Achievement Settings so that Hardcore Mode may be turned off. Also included is the framework required to open AchievementsWindow specifically on the Settings tab.

Source/Core/DolphinQt/Config/HardcoreWarningWidget.h

@@ -0,0 +1,30 @@
+// Copyright 2023 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#ifdef USE_RETRO_ACHIEVEMENTS
+#include <QWidget>
+
+class QLabel;
+class QPushButton;
+
+class HardcoreWarningWidget : public QWidget
+{
+  Q_OBJECT
+public:
+  explicit HardcoreWarningWidget(QWidget* parent);
+
+signals:
+  void OpenAchievementSettings();
+
+private:
+  void CreateWidgets();
+  void ConnectWidgets();
+
+  void Update();
+
+  QLabel* m_text;
+  QPushButton* m_settings_button;
+};
+#endif  // USE_RETRO_ACHIEVEMENTS