Add foundation

Toolkit.Foundation/IConfigurationSource.cs

@@ -0,0 +1,12 @@
+namespace Toolkit.Foundation;
+
+public interface IConfigurationSource<TConfiguration>
+    where TConfiguration :
+    class
+{
+    bool TryGet(out TConfiguration? value);
+
+    void Set(TConfiguration value);
+
+    void Set(object value);
+}