NavItem should have active prop

From [Bootstrap 4 documentation](https://getbootstrap.com/docs/4.0/components/navbar/#nav)

> Active states—with .active—to indicate the current page can be applied directly to .nav-links or their immediate parent .nav-items.

Currently only NavLink have the active prop.