audio_core: Implement Apple AudioToolbox AAC decoder. (#6510)

src/audio_core/hle/audiotoolbox_decoder.h

@@ -0,0 +1,23 @@
+// Copyright 2023 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "audio_core/hle/decoder.h"
+
+namespace AudioCore::HLE {
+
+class AudioToolboxDecoder final : public DecoderBase {
+public:
+    explicit AudioToolboxDecoder(Memory::MemorySystem& memory);
+    ~AudioToolboxDecoder() override;
+    std::optional<BinaryResponse> ProcessRequest(const BinaryRequest& request) override;
+    bool IsValid() const override;
+
+private:
+    class Impl;
+    std::unique_ptr<Impl> impl;
+};
+
+} // namespace AudioCore::HLE