[enhancement] Decouple Regression Model validation from building a regression model

[hnpl]

What's hard to do? (limit 100 words)

Currently, we do k-fold validation every time we call the constructor [1] of RegressionEstimator. The k-fold validation is private within the class. However, there's a need for using the validator without using the model [2], which calls the EstimatorModel to do k-fold validation. This is confusing.

[1]

xls/xls/estimators/delay_model/delay_model.py

Lines 355 to 360 in 6497966

	self._k_fold_cross_validation(
	self.raw_data_points,
	num_cross_validation_folds,
	max_data_point_error,
	max_fold_geomean_error,
	)

[2]

xls/xls/contrib/integrator/area_model/area_characterization_client_main.py

Lines 405 to 406 in 6497966

	# Validate model
	delay_model.DelayModel(model)

Current best alternative workaround (limit 100 words)

N/A

Your view of the "best case XLS enhancement" (limit 100 words)

Decouple RegressionEstimator validation from constructor, allowing validation without using the model.