VideoCommon: add logic to read a GraphicsMod from configuration

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

@@ -0,0 +1,20 @@
+// Copyright 2022 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <string>
+
+#include <picojson.h>
+
+struct GraphicsModFeatureConfig
+{
+  std::string m_group;
+  std::string m_action;
+  picojson::value m_action_data;
+
+  bool DeserializeFromConfig(const picojson::object& value);
+
+  void SerializeToProfile(picojson::object* value) const;
+  void DeserializeFromProfile(const picojson::object& value);
+};