[Fellowship Nominations] Add filtering by Specialties

Feature Request

Description

On https://scipost.org/colleges/nominations/, include filter by profile's Specialties. The filter should take into account that nominated profiles without defined specialties can exist. We could include "None", "undefined", "------", or equivalent as a filter criterion deprecating the "Needs specialties" filter if possible.

Related Issues

• Thematically related to #170 (closed)