with series label placement setting if available while
importing xlsx chart.

Adds unit test in chart2import.cxx that asserts one of
the point label setting in the bugzilla xlsx document.

Change-Id: I8bc04fd569f94a19633666ffdc51b61ac719e8a9
Reviewed-on: https://gerrit.libreoffice.org/40860Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Dennis Francis <dennis.francis@collabora.co.uk>