Update custom constraint workflow

[amontanez24]

Problem Description

As a user, it would be helpful to treat my custom constraints similarly to normal constraint classes, while also having a clear way to distinguish them.

Acceptance criteria

• Change the name of create_custom_constraint to create_custom_constraint_class
• Add a method called load_custom_constraint_classes
  • Parameters
    • filepath: Path to file where custom constraints are defined
    • class_names: The names of the constraint classes to import from that file
  • The method should import the constraint class objects from that file as the name provided in the class_names list
  • Error:
    • Ensure that the constraint_name isn't already defined in the module
      Error: The constraint 'MyConstraintClass' already exists. Please choose a different 'constraint_name'.

Expected behavior

In one file, create the constraint classes

# Example: Defining a custom constraint
def is_valid_fn():
  pass

def my_transform_fn():
  pass

Constraint1 = create_custom_constraint_class(
  is_valid_fn=my_is_valid_fn,
  transform_fn=my_transform_fn,
  reverse_transform_fn=my_reverse_fn,
)

Constraint2 = create_custom_constraint_class(
  is_valid_fn=my_is_valid_fn,
  transform_fn=my_transform_fn,
  reverse_transform_fn=my_reverse_fn,
)

In your script

# separate file: creating a constraint
from sdv.single_table import GaussianCopulaSynthesizer

synthesizer = GaussianCopulaSynthesizer(metadata)


# workaround for
# from foldername.my_custom_constraint import Constraint1, Constraint2
synthesizer.load_custom_constraint_classes(
   filepath='foldername/my_custom_constraint.py',
   class_names=['Constraint1', 'Constraint2']
)

age_lt_child = {
  'constraint_class': 'Constraint1',
  'constraint_parameters': {
    'column_name': 'my_column_name',
    'custom_param_1': 34,
    'custom_param_2': True
}}

age_lt_parent = {
  'constraint_class': 'Inequality',
  'constraint_parameters': {
    'low_column_name': 'age',
    'high_column_name': 'parent_age'
  }
}
synthesizer.add_constraints([age_lt_child, age_lt_parent])

Additional context

Currently, the create_custom_constraints requires the constraint_name to contain the name that would be used to import (ie. foler.file.class_name). We want users to be able to refer to the name of the class directly, so we want to use the load_custom_constraint_classes method to add the class to the namespace so it can be imported later by just the class name