Clean up Experiment List Parmest Code

[smartin71]

Summary

List of items to update to extend/clean up the new experiment list version of the parmest code.

Description

• Create additional built in objective expressions in an Enum class which includes SSE (see SSE function below)
• Clean up the use of theta_names through out the code. The Experiment returns the CUID of each theta and this can be used directly (instead of the name)
• Clean up the use of updated_theta_names, model_theta_names, estimator_theta_names. Not sure if estimator_theta_names is the union or intersect of thetas in each model
• _return_theta_names should no longer be needed
• Generally, theta ordering is not preserved by pyomo, so we should check that ordering matches values for each function, otherwise results will be wrong and/or inconsistent
• return model object (m.k1) and CUIDs in dataframes instead of names ("k1")
• Use pyomo's config checking system to check parmest Estimator inputs.