Migrate adding and validating constraints to BaseSynthesizer

[amontanez24]

Problem Description

As a user, it would be nice if the metadata used through the SDV ecosystem was the same. For some tools, constraints are irrelevant and so having them in the metadata is confusing.

In order to make metadata consistent throughout our ecosystem, we want to separate constraints from it.

Acceptance criteria

• Move all functionality involving constraints in the metadata into the BaseSynthesizer class. This includes
  • Validating constraints
  • Adding constraints
• Instead of add_constraint, create a new add_constraints method
  • Parameters
    • constraints - List of constraints described as dicts in the following format:
      {'constraint_class': NAME, 'constraint_parameters': {'param_1': ..., 'param_2': ...}}
  • Error Handling: Perform the same validation & error handling that we are already doing. Note that we always have access to the metadata because it is required when instantiating the synthesizer.
    • If the user has already fit the synthesizer, warn them that they need to refit it.
      Warning: For these constraints to take effect, please refit the synthesizer using 'fit'
  • If called multiple times, continue to add to the existing list of constraints.

Expected behavior

age_is_positive = {
  'constraint_class': 'Positive',
  'constraint_parameters': {
    'column': 'age',
    'strict_boundaries': True
  }
}

synthesizer.add_constraints(constraints=[age_is_positive])

Additional context

• On top of moving the constraint logic to the BaseSynthesizer there are some other key changes. The new method for adding constraints take in a list instead of an individual constraint dictionary. Additionally, the format of the constraint dictionary is different as the parameters are now in a nested dict. This means that some logic around the validation code will likely need to change.
• The metadata_upgrader will no longer need to update constraints. The code for converting constraints can stay but remove the conversion from convert_metadata