Save links depending on preferences set
Options -> Load/Save -> General -> Save URLs relative to ...

Change-Id: I96d06cfdc405d1e1254515106926374aee279f6c
Reviewed-on: https://gerrit.libreoffice.org/44785Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Szymon Kłos <szymon.klos@collabora.com>