V9: Fix granular permissions for user groups (#11577)

* Fixes the treepicker for granular permissions to use a select callback instead of submit with the full selection

* Introduced UserGroup2NodeDto table, to allow users to save empty arrays of permissions

* Cleanup

* Fixed null issue in audit logging

* Fixed migration

* Fixed GetDeleteClauses

* Fixes for SqlCE, do not run multiple comments on one sql request

* Align behavior between content>permissions and usergroups>granularPpermissions

- It is now possible to save default values in content>permissions like in usergroups>granularPpermissions
- It is now possible to differentiate between we save an empty collection and we remove the granular permissions in content>permissions

* Fix comments

Co-authored-by: Andy Butland <abutland73@gmail.com>
Co-authored-by: Bjarke Berg <mail@bergmania.dk>

src/Umbraco.Core/Models/ContentEditing/UserGroupPermissionsSave.cs

@@ -10,7 +10,7 @@ namespace Umbraco.Cms.Core.Models.ContentEditing
     /// Used to assign user group permissions to a content node
     /// </summary>
     [DataContract(Name = "contentPermission", Namespace = "")]
-    public class UserGroupPermissionsSave : IValidatableObject
+    public class UserGroupPermissionsSave
     {
         public UserGroupPermissionsSave()
         {
@@ -28,13 +28,5 @@ namespace Umbraco.Cms.Core.Models.ContentEditing
         /// </summary>
         [DataMember(Name = "permissions")]
         public IDictionary<int, IEnumerable<string>> AssignedPermissions { get; set; }
-
-        public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
-        {
-            if (AssignedPermissions.SelectMany(x => x.Value).Any(x => x.IsNullOrWhiteSpace()))
-            {
-                yield return new ValidationResult("A permission value cannot be null or empty", new[] { "Permissions" });
-            }
-        }
     }
 }