Refactor Enrich class to improve cohesion

[valeriocos]

The class Enrich should be refactored since it includes methods that do a great variety of actions such as handling identities and implementing studies. Furthermore, studies represent a danger in terms of cohesion since (i) they may need specific methods that aren't needed for the Enrich class/subclasses and (ii) depending on their number, they can cause the class's LOC to grow considerably.

Under this perspective, identity-related and study-related methods should be moved (if possible) to dedicated modules to improve the cohesion and comprehension of this class.