Addition of Enable Contour and Edit Contour button to the sidebar

Change-Id: I9cadbcc9643b9fc87b3dbe3a9a2355cd674d1e53
Reviewed-on: https://gerrit.libreoffice.org/17324Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>