Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Messages/Client/Calendar/ScrollToDateMessage.cs

@@ -0,0 +1,10 @@
+using System;
+
+namespace Wino.Messaging.Client.Calendar
+{
+    /// <summary>
+    /// Raised when requested date is already loaded into calendar flip view to scroll to it.
+    /// </summary>
+    /// <param name="Date">Date to scroll.</param>
+    public record ScrollToDateMessage(DateTime Date);
+}