DOCX import: recurse into w:ins in groupshape text

Groupshape text is provided by editeng, redlining is available in Writer
text only. But still, instead of ignoring both deletions and insertions
in group shape text, we could at least show the latest version
correctly, i.e. ignore deletions but import insertions.

Change-Id: I12df2ca1a8d27f9496a8036e521f8820d7075053
(cherry picked from commit e6300f83d08fd959596551dcd660eb0fbfb248a6)