Add support for Crypten in worker

[gmuraru]

Is your feature request related to a problem? Please describe.
A feature request. Currently, for CrypTen we add all the methods that are "specific" for this framework into the BaseWorker and we need to have a solution to register/unregister those operations.

Describe the solution you'd like
Have separate methods to add/remove support for CrypTen

Describe alternatives you've considered
Have dedicated workers, but see the discussion from here

Additional context
Add any other context or screenshots about the feature request here.