Resolve "Search for students in the system functionality for coordinators"

Closes #189 (closed) Currently you can find anyone in the system. That functionality was added with the offer positions button which allows you to search with identifiers anyone in the system. This MR/issue simply adds an extra UI search page for coordinators to see it better. We could consider refactoring these searches to only find students. For some reason when I implemented this teachers also had the student role?