Refactor LoginPage to MVVM

Jugenddienst Stunden/Converter/EventArgsPassThroughConverter.cs

@@ -0,0 +1,8 @@
+using System.Globalization;
+
+namespace Jugenddienst_Stunden.Converter;
+
+public sealed class EventArgsPassThroughConverter : IValueConverter {
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) => value;
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) => value;
+}