Add publication specific search interface

[dersmon]

Currently each publication in each project can have its own search index, but the search interface will only ever work on one of the publication indices via an "project" alias.

This makes searching old publications impossible, and might cause confusion when navigating (because you might go from an old publication to search and are not aware that you are now seeing the most recent data).

A publication specific search gives us an opportunity to show the results on the publications map, and potential also to search by drawing a polygon.