Add USB passthrough setting and USBUtils

This adds a USB passthrough setting to ConfigManager and everything
needed for the UI to show and manage the whitelist properly.

Source/Core/UICommon/USBUtils.h

@@ -0,0 +1,20 @@
+// Copyright 2017 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <map>
+#include <string>
+#include <utility>
+
+#include "Common/CommonTypes.h"
+
+namespace USBUtils
+{
+void Init();
+void Shutdown();
+
+std::map<std::pair<u16, u16>, std::string> GetInsertedDevices();
+std::string GetDeviceName(std::pair<u16, u16> vid_pid);
+}  // namespace USBUtils