Created new show/hide all comments button for calc by
ShowAnnotations command. Unifyied writer, calc and impress's
ShowAnnotations slot.

Change-Id: I27149d09ee1763b84258c5e0c890a9628c8874c0
Signed-off-by: Gulsah Kose <gulsah.1004@gmail.com>
Reviewed-on: https://gerrit.libreoffice.org/36697Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Eike Rathke <erack@redhat.com>