SwXShape: getter for ChainNext/PrevName UNO property

Change-Id: I7e4fffabf6b1d96a458a3afd141f86d0e4565230
CppunitTest_sw_ooxmlsdrexport: clean up XPath expressions in testFDO77122

Change-Id: I1f8737bbe128c747c84c67e8ba8000ecef1ed4f7