Facilitate a way to customize quick search in WebUI

There is a request from a client to be able to customize the quick search in WebUI. The only way I know to do this would be to override the nuxeo-app.html , which would be quite dangerous. I think it would be very valuable to add this improvement to the platform or provide a less dangerous way to do so. This request is specifically for 10.10

Please feel free to reach out for any clarification