Add foundation

Toolkit.Foundation/ContentTemplateDescriptorProvider.cs

@@ -0,0 +1,18 @@
+using System.Xml.Linq;
+
+namespace Toolkit.Foundation;
+
+public class ContentTemplateDescriptorProvider(IEnumerable<IContentTemplateDescriptor> contentTemplates) :
+    IContentTemplateDescriptorProvider
+{
+    public IContentTemplateDescriptor? Get(object key)
+    {
+        if (contentTemplates.FirstOrDefault(x => x.Key.Equals(key) || x.Key.Equals($"{key}".Replace("ViewModel", "")))
+            is IContentTemplateDescriptor viewModelTemplate)
+        {
+            return viewModelTemplate;
+        }
+
+        return default;
+    }
+}