Port emojier away from deprecated I18N_NOOP

This is rather dirty, the category table should hold KLazyLocalizedString instances rather than QStrings of the untranslated message, and actual translation should be done by calling toString() on those, to avoid duplicating the context.

That however isn't easily possible here as the translation happens on the QML side, after using the untranslated string in a mapping table for icons. So this has to do for now.