Add support for audio playback via audout

Adds an audio manager to state to manage the creation of audio tracks and an audout service implementation that interfaces with it.

app/src/main/cpp/skyline/audio.h

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <queue>
+#include <oboe/Oboe.h>
+
+#include <kernel/types/KEvent.h>
+#include <audio/track.h>
+#include "common.h"
+
+namespace skyline::audio {
+    /**
+     * @brief The Audio class is used to mix audio from all tracks
+     */
+    class Audio : public oboe::AudioStreamCallback {
+      private:
+        const DeviceState &state; //!< The state of the device
+        oboe::ManagedStream outputStream; //!< The output oboe audio stream
+        std::vector<std::shared_ptr<audio::AudioTrack>> audioTracks; //!< Vector containing a pointer of every open audio track
+
+      public:
+        Audio(const DeviceState &state);
+
+        /**
+         * @brief Opens a new track that can be used to play sound
+         * @param channelCount The amount channels that are present in the track
+         * @param sampleRate The sample rate of the track
+         * @param releaseCallback The callback to call when a buffer has been released
+         * @return A shared pointer to a new AudioTrack object
+         */
+        std::shared_ptr<AudioTrack> OpenTrack(int channelCount, int sampleRate, const std::function<void()> &releaseCallback);
+
+        /**
+         * @brief Closes a track and frees its data
+         * @param track The track to close
+         */
+        void CloseTrack(std::shared_ptr<AudioTrack> &track);
+
+        /**
+         * @brief The callback oboe uses to get audio sample data
+         * @param audioStream The audio stream we are being called by
+         * @param audioData The raw audio sample data
+         * @param numFrames The amount of frames the sample data needs to contain
+         */
+        oboe::DataCallbackResult onAudioReady(oboe::AudioStream *audioStream, void *audioData, int32_t numFrames);
+    };
+}