Rework navigation so we can resolve by key now

Toolkit.UI.WinUI/Parameter.cs

@@ -0,0 +1,30 @@
+using Microsoft.UI.Xaml;
+using System.Xml.Linq;
+
+namespace Toolkit.WinUI;
+
+public class Parameter :
+    DependencyObject
+{
+    public static readonly DependencyProperty KeyProperty =
+        DependencyProperty.Register(nameof(Key),
+            typeof(object), typeof(Parameter),
+                new PropertyMetadata(null));
+
+    public static readonly DependencyProperty ValueProperty =
+            DependencyProperty.Register(nameof(Value),
+            typeof(string), typeof(Parameter),
+                new PropertyMetadata(null));
+
+    public string Key
+    {
+        get => (string)GetValue(KeyProperty);
+        set => SetValue(KeyProperty, value);
+    }
+
+    public object Value
+    {
+        get => GetValue(ValueProperty);
+        set => SetValue(ValueProperty, value);
+    }
+}