Add Hotkeys for Skylanders Portal and Infinity Base Menus

Adds two new hotkeys to open the menus for emulated USB devices- Skylanders Portal of Power and the Infinity Base. (Hotkeys only active when game is running).

Portal menu: Default is <Ctrl+P>.
Infinity base: Default is <Ctrl+I>

Source/Core/DolphinQt/Config/Mapping/HotkeyUSBEmu.h

@@ -0,0 +1,26 @@
+#pragma once
+// Copyright 2023 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "DolphinQt/Config/Mapping/MappingWidget.h"
+
+class QHBoxLayout;
+
+class HotkeyUSBEmu final : public MappingWidget
+{
+  Q_OBJECT
+public:
+  explicit HotkeyUSBEmu(MappingWindow* window);
+
+  InputConfig* GetConfig() override;
+
+private:
+  void LoadSettings() override;
+  void SaveSettings() override;
+  void CreateMainLayout();
+
+  // Main
+  QHBoxLayout* m_main_layout;
+};