Ensure containers show up in the menu when they are created

Toolkit.Foundation/ValueStore.cs

@@ -0,0 +1,9 @@
+namespace Toolkit.Foundation;
+
+public class ValueStore<T> :
+    IValueStore<T>
+{
+    public T? Value { get; private set; }
+
+    public void Set(T value) => Value = value;
+}