Bring back C# sample logging!

samples/CSharpWpf/MemoryLogger.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Text;
+using Velopack.Logging;
+
+namespace CSharpWpf;
+
+public class LogUpdatedEventArgs : EventArgs
+{
+    public string Text { get; set; }
+}
+
+public class MemoryLogger : IVelopackLogger
+{
+    public event EventHandler<LogUpdatedEventArgs> LogUpdated;
+    private readonly StringBuilder _sb = new StringBuilder();
+
+    public IDisposable BeginScope<TState>(TState state)
+    {
+        return null;
+    }
+
+    public override string ToString()
+    {
+        lock (_sb) {
+            return _sb.ToString();
+        }
+    }
+
+    public void Log(VelopackLogLevel logLevel, string message, Exception exception)
+    {
+        lock (_sb) {
+            message = $"{logLevel}: {message}";
+            if (exception != null) message += "\n" + exception.ToString();
+            Console.WriteLine("log: " + message);
+            _sb.AppendLine(message);
+            LogUpdated?.Invoke(this, new LogUpdatedEventArgs { Text = _sb.ToString() });
+        }
+    }
+}