fix: Audio samples mute optimization (#969)

* Audio samples mute optimization

    private static void Test1()
    {
        InitData(out var data);

        var sw = Stopwatch.StartNew();
        for (int i = 0; i < data.Length; i++)
        {
            data[i] = 0;
        }
        sw.Stop();

        Debug.Log($"test1: {sw.ElapsedMilliseconds}"); //About 50
    }

    private static void Test2()
    {
        InitData(out var data);

        var sw = Stopwatch.StartNew();
        Array.Clear(data, 0, data.Length);
        sw.Stop();

        Debug.Log($"test2: {sw.ElapsedMilliseconds}");//About 30
    }

    private static void InitData(out float[] data)
    {
        data = new float[100_000_000];
        UnityEngine.Random.InitState(1);
        for (int i = 0; i < data.Length; i++)
        {
            data[i] = UnityEngine.Random.Range(0.0f, 1.0f);
        }
    }

* Update AudioCustomFilter.cs

Runtime/Scripts/AudioCustomFilter.cs

@@ -1,3 +1,4 @@
+using System;
 using UnityEngine;
 
 namespace Unity.WebRTC
@@ -41,10 +42,7 @@ void OnAudioFilterRead(float[] data, int channels)
 
             if (sender && !loopback)
             {
-                for (int i = 0; i < data.Length; i++)
-                {
-                    data[i] = 0;
-                }
+                Array.Clear(data, 0, data.Length);
             }
         }
     }