Required on view models (#15356)

* Added required on view models

* Updated OpenApi.json

* mark all fields required

* Force non-nullable as required.

* Missing import

* Update OpenApi.json

---------

Co-authored-by: Mads Rasmussen <madsr@hey.com>

src/Umbraco.Cms.Api.Management/ViewModels/DynamicRoot/DynamicRootRequestModel.cs

@@ -0,0 +1,6 @@
+namespace Umbraco.Cms.Api.Management.ViewModels.DynamicRoot;
+
+public class DynamicRootRequestModel
+{
+    
+}