MemberAdminWindow+DeliveryAdminWindow: Add button to jumpt to member (predecessor)

Elwig/Windows/DeliveryAdminWindow.xaml.cs

@@ -1789,5 +1789,10 @@ namespace Elwig.Windows {
             }
             CheckBox_Changed(sender, evt);
         }
+
+        private void MemberReferenceButton_Click(object sender, RoutedEventArgs evt) {
+            if (MemberInput.SelectedItem is not Member m) return;
+            App.FocusMember(m.MgNr);
+        }
     }
 }