Play snd0.at9 during the startup splash screen (#1545)

launcher: play snd0.at9 on title selection

src/launcher/include/titleSound.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <QByteArray>
+#include <QFutureWatcher>
+#include <QObject>
+#include <QPromise>
+#include <QString>
+#include <QThreadPool>
+
+#include <vector>
+
+struct SDL_AudioStream;
+
+class TitleSound final: public QObject {
+public:
+	explicit TitleSound(QObject* parent = nullptr);
+	~TitleSound() override;
+
+	void SetTitle(const QString& base);
+
+private:
+	struct Sound {
+		std::vector<float> pcm;
+		int                channels = 0;
+		int                rate     = 0;
+	};
+
+	static Sound Decode(const QByteArray& data, const QPromise<Sound>& promise);
+	void         Stop();
+
+	QThreadPool           m_decode_pool;
+	QFutureWatcher<Sound> m_decode;
+	QString               m_base;
+	SDL_AudioStream*      m_stream            = nullptr;
+	bool                  m_audio_initialized = false;
+};