fdo#69644 - fix docx export of wrong number and width of columns

When the DOCX exporter exported a table, it filled the table
column definitions with the column sizes of the FIRST row only.
This was ok for tables that have the same columns on all rows,
but for more complex tables with different cell widths - the
filter exported the wrong number of columns and the wrong width.
A followup fix would fix the rounding problems there still are
with the column widths that are exported in the table
definition.

Conflicts:
	sw/qa/extras/ooxmlexport/ooxmlexport.cxx

Change-Id: Ie95dfe60b1c1811776433e457ca04e728623e01e
Reviewed-on: https://gerrit.libreoffice.org/6290