Extended Parmest Capability for weighted SSE objective

[slilonfe5]

Fixes # .

Summary/Motivation:

Currently, the Parmest SSE objective does not support measurements in different units. This work adds a new capability (i.e., weighted SSE) to Parmest to handle measurements in different units.

Changes proposed in this PR:

• Added a new weighted SSE calculation
• Added a new covariance matrix calculation for the weighted SSE objective

Legal Acknowledgement

By contributing to this software project, I have read the contribution guide and agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the BSD license.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[slilonfe5]

@adowling2 @djlaky

[adowling2]

@slilonfe5 Here is some quick feedback

compute_jacobian function

• Make this a private method by adding _ to the function name
• Add as an argument to the function relative_perturbation
• In the document string, explain this is using forward (?) finite difference
• Add as an argument the solver object. You can make the default Ipopt.

Feedback on the compute_FIM method:

• Add relative_tolerance and solver as arguments
• Also add a check that error_list must be the same length as y_hat_list
• Add a debugging step for the linear algebra error, compute the condition number of the Jacobian matrix and print it out
• Why would you ever get a linear algebra error for just matrix multiplication? Is this check even needed?