component: embl breadcrumb path for active path

Shows the link for the active breadcrumb if it is not the current page.

That is, if the active crumb might be "Jane Group":

- We shouldn't show it as a link if we're on the group homepage
- We should show it as a link if we're not on the homepage

For groups we might also be able to rely on the group header, but this won't be there for all types of pages (landing pages, for example) and ensures a consitent behaviour across embl.org