Added links to Bulksearch in the header and the search bar.

[benbdeitch]

Closes #9715

This feature add some much needed linking to the new Bulk Search feature. It can now be selected from either the 'browse' menu, or the searchbar, with either option redirecting you to the page itself.

Technical

Testing

After loading up your local instance, try out both links. They should redirect you properly.

Screenshot

Stakeholders

@cdrini