LibAudio: Added playback control features to audio server

LibAudio now supports pausing playback, clearing the buffer queue,
retrieving the played samples since the last clear and retrieving
the currently playing shared buffer id

Servers/AudioServer/AudioServer.ipc

@@ -9,6 +9,11 @@ endpoint AudioServer
 
     // Buffer playback
     EnqueueBuffer(i32 buffer_id, int sample_count) => (bool success)
+    SetPaused(bool paused) => ()
+    ClearBuffer(bool paused) => ()
 
+    //Buffer information
     GetRemainingSamples() => (int remaining_samples)
+    GetPlayedSamples() => (int played_samples)
+    GetPlayingBuffer() => (i32 buffer_id)
 }