Added the new InteropGrabBag property to the Shape
service and modified the JUnit UNO unit tests for
it.

Added specific implementation in the svx module
for the SvxShape class.

This new property is intended by now for its usage
on preserving OOX's Smart-Art but it could also be
used for preserving other attributes for
interoperability among document formats.

Change-Id: Idc7a8e91592399ff05effd4da6eaa2935f8f4d42
Reviewed-on: https://gerrit.libreoffice.org/5769Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>