SIFR: add missing icons for calc's function wizard and sum toolbar buttons

Change-Id: Ia3fd2f71ee68e03a409c00d146ad0647e305a6f2
Reviewed-on: https://gerrit.libreoffice.org/12109
Reviewed-by: Matthew Francis <mjay.francis@gmail.com>
Tested-by: Matthew Francis <mjay.francis@gmail.com>