DolphinQt: Add GBA TAS input window

When emulated GBAs were added to Dolphin, it was possible to control them
using the GC TAS input window. (Z was mapped to Select.) Unaware of this,
I broke the functionality in b296248.

To make it possible to control emulated GBAs using TAS input again,
I'm adding a proper TAS input window for GBAs, with a real Select button
and no analog controls.

Source/Core/DolphinQt/TAS/GBATASInputWindow.h

@@ -0,0 +1,39 @@
+// Copyright 2022 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "DolphinQt/TAS/TASInputWindow.h"
+
+class QGroupBox;
+class QHideEvent;
+class QShowEvent;
+class QSpinBox;
+class TASCheckBox;
+
+class GBATASInputWindow final : public TASInputWindow
+{
+  Q_OBJECT
+public:
+  explicit GBATASInputWindow(QWidget* parent, int controller_id);
+
+  void hideEvent(QHideEvent* event) override;
+  void showEvent(QShowEvent* event) override;
+
+private:
+  int m_controller_id;
+
+  InputOverrider m_overrider;
+
+  TASCheckBox* m_b_button;
+  TASCheckBox* m_a_button;
+  TASCheckBox* m_l_button;
+  TASCheckBox* m_r_button;
+  TASCheckBox* m_select_button;
+  TASCheckBox* m_start_button;
+
+  TASCheckBox* m_left_button;
+  TASCheckBox* m_up_button;
+  TASCheckBox* m_down_button;
+  TASCheckBox* m_right_button;
+};