Update transformer assignment logic for handling pii

[R-Palazzo]

Problem Description

Inside the metadata, a user can add a boolean information indicating wether a column is a pii. The current logic is to assign AnonymizedFaker whenever this field is True.

Expected behavior

Now that there are some pii sdtypes that have premium transformers (email/phone number...), those transformers should be assigned regardless on the pii field.
The new logic for pii sdtypes:

• If a user has access to the premium transformer for this sdtype, assign it.
• If a user doesn't have access to a premium transformer, then
  • If pii=True, assign AnonymizedFaker
  • If pii=False, assign the default categorical transformer, currently UniformEncoder.

Additional context

After the changes, the code below should assign the premium transformer for premium users and AnonymizedFaker otherwise.

data = pd.DataFrame({
    'email': ['sdv@sdv.dev', 'info@datacebo.com', 'info@gmail.co.uk', None],
    'numerical': [0, 1, 2, 3],
})

metadata = SingleTableMetadata().load_from_dict({
    'columns': {
        'email': {'sdtype': 'email', 'pii': True},
        'numerical': {'sdtype': 'numerical'},
    }
})

# Run
synthesizer = GaussianCopulaSynthesizer(metadata)
synthesizer.fit(data)