Issue #3347943 by pdureau, Grimreaper: Better variants to HTML class conversions

templates/patterns/accordion/pattern-accordion.html.twig

templates/patterns/alert/pattern-alert.html.twig

templates/patterns/button/pattern-button.html.twig

...ates/patterns/button_group/pattern-button-group.html.twig

templates/patterns/carousel/pattern-carousel.html.twig

templates/patterns/dropdown/pattern-dropdown.html.twig

...es/patterns/dropdown_item/pattern-dropdown-item.html.twig

templates/patterns/list/pattern-list.html.twig

templates/patterns/list_group/pattern-list-group.html.twig

...atterns/list_group_item/pattern-list-group-item.html.twig

templates/patterns/nav/pattern-nav.html.twig

templates/patterns/navbar/pattern-navbar.html.twig

templates/patterns/navbar_nav/pattern-navbar-nav.html.twig

templates/patterns/pagination/pattern-pagination.html.twig

templates/patterns/progress/pattern-progress.html.twig

templates/patterns/table/pattern-table.html.twig