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/Handlers/AuditNotificationsHandler.cs

@@ -226,7 +226,7 @@ namespace Umbraco.Cms.Core.Handlers
             foreach (var perm in perms)
             {
                 var group = _userService.GetUserGroupById(perm.UserGroupId);
-                var assigned = string.Join(", ", perm.AssignedPermissions);
+                var assigned = string.Join(", ", perm?.AssignedPermissions ?? Array.Empty<string>());
                 var entity = _entityService.Get(perm.EntityId);
 
                 _auditService.Write(performingUser.Id, $"User \"{performingUser.Name}\" {FormatEmail(performingUser)}", PerformingIp,