replace v6 with experimental v7 code

src/MpvNet.Extension/ExampleExtension/ExampleExtension.cs

@@ -0,0 +1,24 @@
+
+namespace MpvNet.Extension.ExampleExtension;
+
+public class Extension : IExtension
+{
+    public MpvClient Player { get; set; }
+
+    public Extension()
+    {
+        Player = Global.Player.CreateNewPlayer("example");
+        Player.ObservePropertyBool("fullscreen", FullscreenChange);
+        Player.FileLoaded += Player_FileLoaded;
+    }
+
+    void Player_FileLoaded()
+    {
+        Terminal.Write("File loaded: " + Player.GetPropertyString("path"));
+    }
+
+    void FullscreenChange(bool value)
+    {
+        Player.CommandV("show-text", "fullscreen: " + value);
+    }
+}