Add foundation

Toolkit.Foundation/ContentTemplateDescriptor.cs

@@ -0,0 +1,16 @@
+namespace Toolkit.Foundation;
+
+public class ContentTemplateDescriptor(object key,
+    Type viewModelType, 
+    Type viewType,
+    params object[]? parameters) :
+    IContentTemplateDescriptor
+{
+    public object Key => key;
+
+    public object[]? Parameters => parameters;
+
+    public Type ContentType => viewModelType;
+
+    public Type TemplateType => viewType;
+}