DOCX import: handle character format of dateTime SDT

Change-Id: Ia8966745b1ed63ae7de2ad0d673faff8b8804d63
DOCX export: handle character format of dateTime SDT

The trick is that this logic has been already implemented for table
styles, so just reuse that.

Change-Id: I5b094fece244da8cf0857ce829a54aa7c124e280
CppunitTest_sw_ooxmlexport / testSdt2Run: one more assert

Change-Id: Ic5f2f86992c91b054d4db18174396bd2480f639b
Update sw/qa/extras/README

The run() method is gone since 4.2.

Change-Id: Ia7a9932001dff7834e960885096468148d47738a