API: Make `ExtraButtonComponent` accessible

Not sure if this is the place to post this sort of stuff or not (apologies if not!), but it seems the ExtraButtonComponent component generates a plain ol’ div instead of a button like its ButtonComponent counterpart does. Is there a reason behind this?

For accessibility purposes it would be better to have it be a button so that we get things like its role and the ability to tab to it by default.