Implement audout GetAudioOutPlayedSampleCount

Used in Ninja Gaiden games.

src/audio_core/stream.h

@@ -89,6 +89,11 @@ public:
         return sample_rate;
     }
 
+    /// Gets the number of samples played so far
+    [[nodiscard]] u64 GetPlayedSampleCount() const {
+        return played_samples;
+    }
+
     /// Gets the number of channels
     [[nodiscard]] u32 GetNumChannels() const;
 
@@ -106,6 +111,7 @@ private:
     [[nodiscard]] std::chrono::nanoseconds GetBufferReleaseNS(const Buffer& buffer) const;
 
     u32 sample_rate;                  ///< Sample rate of the stream
+    u64 played_samples{};             ///< The current played sample count
     Format format;                    ///< Format of the stream
     float game_volume = 1.0f;         ///< The volume the game currently has set
     ReleaseCallback release_callback; ///< Buffer release callback for the stream