Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Messages/Client/Calendar/GoToCalendarDayMessage.cs

@@ -0,0 +1,10 @@
+using System;
+
+namespace Wino.Messaging.Client.Calendar
+{
+    /// <summary>
+    /// Raised when specific date is requested to be clicked on CalendarView.
+    /// </summary>
+    /// <param name="DateTime">Date to be navigated.</param>
+    public record GoToCalendarDayMessage(DateTime DateTime);
+}