Add first event with a key value

Toolkit.Foundation/ActivateEventArgs.cs

@@ -12,5 +12,20 @@ public record ActivateEventArgs<TValue>
     public ActivateEventArgs()
     {
 
+    }
+}
+
+public record ActivateEventArgs<TKey, TValue>
+{
+    public TValue? Value { get; }
+
+    public ActivateEventArgs(TValue value)
+    {
+        Value = value;
+    }
+
+    public ActivateEventArgs()
+    {
+
     }
 }