Do not use `header` or `footer` in Cards using `div`

[spaceninja]

By default the Card component renders as an article element. The Card's header and footer sections are rendered using header and footer elements.

However, if you change the Card's element to a div it causes the VO Rotor to display a list of unlabelled banner landmarks. That's because the banner role is removed from header elements when they're a descendent of an article element.

To fix this, we just need to add a bit of conditional logic — if the tag_name is article or section, then header_tag_name should be header and footer_tag_name should be footer. If tag_name is anything else (such as div) then header_tag_name and footer_tag_name should both be div.

Note the same change should be made to the Overview object template.