If we want to replace an image, we have an entry in the context menu for that.

Change-Id: I7a5326fecb72896c0709c9272769b8d51e4a5ca2
Reviewed-on: https://gerrit.libreoffice.org/26947Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>