Add unit-test for 'track changes - paragraph properties changed' preservation

This is a unit-test added to complement the patch that added support
for the preservation of 'Track Changes - Paragraph Properties Changed'
from a DOCX file.

Conflicts:
	sw/qa/extras/ooxmlexport/ooxmlexport.cxx
Reviewed on:
	https://gerrit.libreoffice.org/7401

Change-Id: Ic81a5ac9ee369ae0f1d2f8d1a1fe54ea5e6b7402