Implement K-Anonymity logic in PrivateDatasetWrapper

[aviralgarg05]

The PrivateDatasetWrapper class accepts a k_anonymity parameter in __init__, but it is currently unused in the class implementation.

File: src/agentunit/privacy/wrappers.py

Task:

• Implement logic to enforce k-anonymity on the dataset (or generalizes attributes) if this is intended.
• Or, if not ready, mark it as TODO/NotImplemented or remove the parameter to avoid confusion.