Fixed username update or user delete does not cause asset ownership update

src/Helpers/SynchronizationHelper.cs

@@ -0,0 +1,25 @@
+using Berufsschule_HAM.Models;
+using Berufsschule_HAM.Services;
+
+namespace Berufsschule_HAM.Helpers;
+public static class SynchronizationHelper
+{
+    public static async Task SyncAssetOwnership(LdapService ldap, string oldName, string newName)
+    {
+        bool remove = string.IsNullOrEmpty(newName);
+        string uidString = $"uid={newName}";
+        IEnumerable<AssetModel> assets = await ldap.ListDeviceAsync();
+        var tasks = assets.Where(asset => asset.Owner == $"uid={oldName}").ToList().Select(async asset =>
+        {
+            if (remove)
+            {
+                await ldap.DeleteAttribute(ldap.AssetsBaseDn, "cn", asset.Cn, "owner");
+            }
+            else
+            {
+                await ldap.UpdateAsset(asset.Cn, "owner", uidString);            
+            }
+        });
+        await Task.WhenAll(tasks);
+    }
+}