Core: Add RiivolutionPatcher to apply Riivolution-style patches to a game's file system and memory.

Source/Core/DiscIO/RiivolutionPatcher.h

@@ -0,0 +1,21 @@
+// Copyright 2021 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <vector>
+
+#include "DiscIO/RiivolutionParser.h"
+
+namespace DiscIO
+{
+struct FSTBuilderNode;
+}
+
+namespace DiscIO::Riivolution
+{
+void ApplyPatchesToFiles(const std::vector<Patch>& patches,
+                         std::vector<DiscIO::FSTBuilderNode>* fst,
+                         DiscIO::FSTBuilderNode* dol_node);
+void ApplyPatchesToMemory(const std::vector<Patch>& patches);
+}  // namespace DiscIO::Riivolution