UDPServer: Add configuration UI.

Accessed through button "Alternate Input Sources" in the "Controller Settings" dialog.

Source/Core/DolphinQt/Config/ControllerInterface/ControllerInterfaceWindow.h

@@ -0,0 +1,32 @@
+// Copyright 2019 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <QDialog>
+
+#include "InputCommon/ControllerInterface/ControllerInterface.h"
+
+#if defined(CIFACE_USE_CEMUHOOKUDPSERVER)
+class CemuHookUDPServerWidget;
+#endif
+class QTabWidget;
+class QDialogButtonBox;
+
+class ControllerInterfaceWindow final : public QDialog
+{
+  Q_OBJECT
+public:
+  explicit ControllerInterfaceWindow(QWidget* parent);
+
+private:
+  void CreateMainLayout();
+
+  QTabWidget* m_tab_widget;
+  QDialogButtonBox* m_button_box;
+
+#if defined(CIFACE_USE_CEMUHOOKUDPSERVER)
+  CemuHookUDPServerWidget* m_udpserver_widget;
+#endif
+};