Update with recovered code from VM binaries (Jan 1)

- ShellDemo: Updated all pages with recovered code, added AppShell.cs
- TodoApp: Updated core files, added converters
- XamlBrowser: Added recovered sample

TodoApp/CompletedToOpacityConverter.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Globalization;
+using Microsoft.Maui.Controls;
+
+namespace TodoApp;
+
+public class CompletedToOpacityConverter : IValueConverter
+{
+	public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+	{
+		bool flag = default(bool);
+		int num;
+		if (value is bool)
+		{
+			flag = (bool)value;
+			num = 1;
+		}
+		else
+		{
+			num = 0;
+		}
+		return (((uint)num & (flag ? 1u : 0u)) != 0) ? 0.7 : 1.0;
+	}
+
+	public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+	{
+		throw new NotImplementedException();
+	}
+}