fix(ConsoleViewer): remove unnecessary struct

The `Log` struct was not being used and causing a compile warning.
It has now been deleted.

Assets/VRTK/Prefabs/Resources/Scripts/VRTK_ConsoleViewer.cs

@@ -26,13 +26,6 @@ public class VRTK_ConsoleViewer : MonoBehaviour
     [Tooltip("The colour of the text for an exception log message.")]
     public Color exceptionMessage = Color.red;
 
-    private struct Log
-    {
-        public string message;
-        public string stackTrace;
-        public LogType type;
-    }
-
     private Dictionary<LogType, Color> logTypeColors;
     private ScrollRect scrollWindow;
     private RectTransform consoleRect;