fdo#80536 Add a shortcut to "Edit Mode" menu entry

Change-Id: Ib2535a091cad506c6ce49941361757a9f9e72865
Reviewed-on: https://gerrit.libreoffice.org/11302
Reviewed-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>
Tested-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>