Add foundation

Toolkit.Foundation/ConfigurationChangedHandler.cs

@@ -0,0 +1,21 @@
+namespace Toolkit.Foundation;
+
+public class ConfigurationChangedHandler<TConfiguration, TValue>(ConfigurationValue<TConfiguration, TValue> configurationValue) :
+    INotificationHandler<Changed<TConfiguration>>
+    where TValue :
+    class, new()
+{
+    public Task Handle(Changed<TConfiguration> args,
+        CancellationToken cancellationToken = default)
+    {
+        if (args.Value is TConfiguration configuration)
+        {
+            if (configurationValue.TryUpdate(configuration, out TValue value))
+            {
+
+            }
+        }
+
+        return Task.CompletedTask;
+    }
+}