feat: disabled date related feature.

src/Ursa/Controls/DateTimePicker/IDateSelector.cs

@@ -0,0 +1,17 @@
+namespace Ursa.Controls;
+
+public interface IDateSelector
+{
+    public bool IsValid(DateTime? date); 
+}
+
+public class WeekendDateSelector: IDateSelector
+{
+    public static WeekendDateSelector Instance { get; } = new WeekendDateSelector();
+    
+    public bool IsValid(DateTime? date)
+    {
+        if (date is null) return false;
+        return date.Value.DayOfWeek == DayOfWeek.Saturday || date.Value.DayOfWeek == DayOfWeek.Sunday;
+    }
+}