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.cpp

@@ -0,0 +1,64 @@
+#include "audio.h"
+
+namespace skyline::audio {
+    Audio::Audio(const DeviceState &state) : state(state), oboe::AudioStreamCallback() {
+        oboe::AudioStreamBuilder builder;
+
+        builder.setChannelCount(constant::ChannelCount)
+            ->setSampleRate(constant::SampleRate)
+            ->setFormat(constant::PcmFormat)
+            ->setCallback(this)
+            ->openManagedStream(outputStream);
+
+        outputStream->requestStart();
+    }
+
+    std::shared_ptr<AudioTrack> Audio::OpenTrack(int channelCount, int sampleRate, const std::function<void()> &releaseCallback) {
+        std::shared_ptr<AudioTrack> track = std::make_shared<AudioTrack>(channelCount, sampleRate, releaseCallback);
+        audioTracks.push_back(track);
+
+        return track;
+    }
+
+    void Audio::CloseTrack(std::shared_ptr<AudioTrack> &track) {
+        audioTracks.erase(std::remove(audioTracks.begin(), audioTracks.end(), track), audioTracks.end());
+        track.reset();
+    }
+
+    oboe::DataCallbackResult Audio::onAudioReady(oboe::AudioStream *audioStream, void *audioData, int32_t numFrames) {
+        i16 *destBuffer = static_cast<i16 *>(audioData);
+        int setIndex = 0;
+        size_t sampleI16Size = static_cast<size_t>(numFrames) * audioStream->getChannelCount();
+
+        for (auto &track : audioTracks) {
+            if (track->playbackState == AudioOutState::Stopped)
+                continue;
+
+            track->bufferLock.lock();
+
+            std::queue<i16> &srcBuffer = track->sampleQueue;
+            size_t amount = std::min(srcBuffer.size(), sampleI16Size);
+
+            for (size_t i = 0; i < amount; i++) {
+                if (setIndex == i) {
+                    destBuffer[i] = srcBuffer.front();
+                    setIndex++;
+                } else {
+                    destBuffer[i] += srcBuffer.front();
+                }
+
+                srcBuffer.pop();
+            }
+
+            track->sampleCounter += amount;
+            track->CheckReleasedBuffers();
+
+            track->bufferLock.unlock();
+        }
+
+        if (sampleI16Size > setIndex)
+            memset(destBuffer, 0, (sampleI16Size - setIndex) * 2);
+
+        return oboe::DataCallbackResult::Continue;
+    }
+}