Fix regression of #3543: Missing function to set current language.
Fix regression of #3543: Missing function to set current language.

jwinzer/OpenSlides,FinnStutzenstein/OpenSlides,emanuelschuetze/OpenSlides,FinnStutzenstein/OpenSlides,ostcar/OpenSlides,boehlke/OpenSlides,OpenSlides/OpenSlides,FinnStutzenstein/OpenSlides,boehlke/OpenSlides,boehlke/OpenSlides,FinnStutzenstein/OpenSlides,emanuelschuetze/OpenSlides,CatoTH/OpenSlides,tsiegleauq/OpenSlides,normanjaeckel/OpenSlides,normanjaeckel/OpenSlides,jwinzer/OpenSlides,CatoTH/OpenSlides,jwinzer/OpenSlides,OpenSlides/OpenSlides,normanjaeckel/OpenSlides,jwinzer/OpenSlides,emanuelschuetze/OpenSlides,tsiegleauq/OpenSlides,jwinzer/OpenSlides,CatoTH/OpenSlides,tsiegleauq/OpenSlides,normanjaeckel/OpenSlides,ostcar/OpenSlides,ostcar/OpenSlides,boehlke/OpenSlides,emanuelschuetze/OpenSlides,CatoTH/OpenSlides