(related: fdo#79319) writerfilter: RTF import: fix crash on "fake" pict

The document has a \pict with {\sp{\sn shapeType}{\sv 1}}, i.e. it's
actually a rectangle shape; Word seems to ignore the picture data in
this case, so try to do the same.  Also consolidate the shape creation
in a new function RTFSdrImport::initShape().

(regression from ba9b63d8101197d3fd8612193b1ca188271dfc1a)

(cherry picked from commit 2b9e782497cb962d9ca74a851a1389b0e29df49c)

Conflicts:
	writerfilter/source/rtftok/rtfsdrimport.cxx
	writerfilter/source/rtftok/rtfsdrimport.hxx

Change-Id: Iec94852ddc4c1ca3d8284119e6f1818a8dbb4149
Reviewed-on: https://gerrit.libreoffice.org/10387
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>