Fix docx import of wrap 'Square' for groups

[Regina Henschel]

Hi Miklos (and you all),

I write to you (list in CC) because you are often working in that area.

I cannot continue my actual "3D extrusion" project because groups are 
being imported to Writer incorrectly. So I have tried to fix the import. 
The current state is in https://gerrit.libreoffice.org/c/core/+/114193

Now I stuck, because some unit tests fail with small differences. But 
before I put a lot of time into it, to find whether the values in the 
unit tests are wrong or whether and where my patch is incorrect, I would 
like, if you have a look at the patch in general.

When you want to test it, you need to consider bug tdf#141675 and revert 
the there mentioned patch.

The export is still wrong, and import of custom shapes outside groups 
has still wrong wrap margins. Those would need further patches.

Kind regards
Regina