Add supported for key mediator handelrs

Bitvault/ItemDropdownEntryViewModel.cs

@@ -0,0 +1,12 @@
+using Toolkit.Foundation;
+
+namespace Bitvault;
+
+public partial class ItemDropdownEntryViewModel(IServiceProvider provider,
+    IServiceFactory factory,
+    IMediator mediator,
+    IPublisher publisher,
+    ISubscription subscriber,
+    IDisposer disposer) :
+    Observable(provider, factory, mediator, publisher, subscriber, disposer),
+    IItemEntryViewModel;