Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Core.ViewModels/Data/BreadcrumbNavigationItemViewModel.cs

@@ -0,0 +1,23 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using Wino.Messaging.Client.Navigation;
+
+namespace Wino.Mail.ViewModels.Data
+{
+    public partial class BreadcrumbNavigationItemViewModel : ObservableObject
+    {
+        [ObservableProperty]
+        private string title;
+
+        [ObservableProperty]
+        private bool isActive;
+
+        public BreadcrumbNavigationRequested Request { get; set; }
+
+        public BreadcrumbNavigationItemViewModel(BreadcrumbNavigationRequested request, bool isActive)
+        {
+            Request = request;
+            Title = request.PageTitle;
+            IsActive = isActive;
+        }
+    }
+}