4e97fa0f4e
essentially, this duplicates and converts the service in
xmlscript/source/xmlflat_impexp/
and then converts it to use SvXMLImport APIs, stripping about 3 layers
of unnecessary indirection in the process.
Also improve some exception throwing in sax/ to make the next
programmers life easier when finding the source of exceptions.
Change-Id: I1ac552ee0565349e8322a55f6f609cf9f4521cab
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/89084
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>