Add search to currencies

This page is a capture in the next bucket of the product backlog — a pre-sprint idea, not yet pulled into a sprint as a story.

It should be possible to filter the open currencies by a string. This should be any field. The user needs to know when the list has been filtered. Ideally we should have buttons at the top per field and filter using those. It should go back to database rather than just filter what is available in UI.