only write new element and attributes in ODF 1.2 extended

Change-Id: I038f200f500ef1c6a0815b6332fb17bb2f62282a
Reviewed-on: https://gerrit.libreoffice.org/7221
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>