Add translation for attribution swisstopo private

solve #1334 (mf-geoadmin) change attribution for layer ch.swisstopo.lubis-luftbilder-dritte-firmen and ch.swisstopo.lubis-luftbilder-dritte-kantone.
Need to update table re3.layers_js :

update re3.layers_js set attribution = 'ch.swisstopo.private' where fk_id_dataset = 'ch.swisstopo.lubis-luftbilder-dritte-firmen';
update re3.layers_js set attribution = 'ch.swisstopo.kt' where fk_id_dataset = 'ch.swisstopo.lubis-luftbilder-dritte-kantone';