Merge core project into winui project.

Wino.Mail.WinUI/Converters/GridLengthConverter.cs

@@ -0,0 +1,26 @@
+using System;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Data;
+
+namespace Wino.Converters;
+
+public partial class GridLengthConverter : IValueConverter
+{
+    public object Convert(object value, Type targetType, object parameter, string language)
+    {
+        if (value is double doubleValue)
+        {
+            return new GridLength(doubleValue);
+        }
+        return new GridLength(1, GridUnitType.Auto);
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, string language)
+    {
+        if (value is GridLength gridLength)
+        {
+            return gridLength.Value;
+        }
+        return 0.0;
+    }
+}