This patch adds support in the DOCX importer for the 'table cell redline'
to be sent from the DOCX importer, using UNO (as a property of the
table cell) to the SW core. Once it reaches the 'table cell' - the
'set property' detects this property - and creates an
'SwTableCellRedline' object for it, and adds it to the
'SwExtraRedlineTbl' object.

Change-Id: Iba038f4109d5505b94cea548e73c614b5cc1b637
Reviewed-on: https://gerrit.libreoffice.org/7875Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>