fdo#83848 Add GetAddressConvention to RefButton

Change-Id: I20d633909d3c13bf49998a6cca054ab125b6c991
Reviewed-on: https://gerrit.libreoffice.org/11578
Reviewed-by: Kohei Yoshida <libreoffice@kohei.us>
Tested-by: Kohei Yoshida <libreoffice@kohei.us>