Update MkvInfoReader, Add MkvNode extensions

MkvToolnixWrapper/MkvInfo/Reader/MkvNodeRoot.cs

@@ -0,0 +1,19 @@
+using System.Text;
+
+namespace MkvPropEditWrapper.MkvInfo.Reader;
+
+public class MkvNodeRoot : MkvNode
+{
+    public override NodeType NodeType => NodeType.Root;
+    public override int Depth => -1;
+
+    public MkvNodeRoot()
+        : base(null, "Root".AsMemory())
+    {
+    }
+
+    protected override void AppendSelf(StringBuilder builder)
+    {
+
+    }
+}