Feature13/recommender membership inference attack

[ihanus]

This addition to GuardianAI enables the use of membership inference attacks for recommender systems.

• Additional libraries: torch==2.2.1
• For testing purposes, unit tests have been included in tests/unitary/test_privacy_attacks_recommender.py
• Documentation can be found in docs/source/user_guide/privacy_estimation/privacy_recommender.rst
• The implementation of the recommender attack is based on Zhang et al., 2021. Membership Inference Attacks Against Recommender Systems.

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