VideoCommon: add logic to read a GraphicsMod from configuration

Source/Core/VideoCommon/GraphicsModSystem/Config/GraphicsTargetGroup.h

@@ -0,0 +1,22 @@
+// Copyright 2022 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include <picojson.h>
+
+#include "VideoCommon/GraphicsModSystem/Config/GraphicsTarget.h"
+
+struct GraphicsTargetGroupConfig
+{
+  std::string m_name;
+  std::vector<GraphicsTargetConfig> m_targets;
+
+  bool DeserializeFromConfig(const picojson::object& obj);
+
+  void SerializeToProfile(picojson::object* obj) const;
+  void DeserializeFromProfile(const picojson::object& obj);
+};