LoadZIP Jacobians for new formulations and tests

[nkoukpaizan]

Description

This updates the Jacobian terms computed for LoadZIP and adds Jacobian tests.

Proposed changes

• Replaced the computation of $\frac{\partial h}{\partial w_b}$ with $\frac{\partial h}{\partial y}$, $\frac{\partial f}{\partial y}$ and $\frac{\partial f}{\partial w_b}$ for the modified model implementation
• Added a Jacobian test comparing Enzyme Jacobians and DependencyTracking Jacobians
• Added an initialization for internal variables
• Bug fix for the GovernorTest, where the Jacobian entries were not deduplicated

Checklist

• All tests pass.
• Code compiles cleanly with flags -Wall -Wpedantic -Wconversion -Wextra.
• The new code follows GridKit™ style guidelines.
• There are unit tests for the new code.
• The new code is documented.
• The feature branch is rebased with respect to the target branch.
• [N/A] I have updated CHANGELOG.md to reflect the changes in this PR. If this is a minor PR that is part of a larger fix already included in the file, state so.

Further comments

• The residual test fails after activating the LoadZIPTests. Either the model implementation or the answer keys are incorrect. @abirchfield Please check.
• The $\frac{\partial f}{\partial y}$ is failing to build. This is because the internal variables are all algebraic, so $\frac{\partial f}{\partial y_p}$ is null. I need to implement a workaround for this. Implemented a workaround that I don't particularly like. We can discuss more offline.

[pelesh]

CC @PhilipFackler

[pelesh]

I believe residual tests were failing because of incorrect answer key. I updated test answers with correct numbers and pushed to this branch.

I also tweaked model parameters so that unit test answers are integer numbers for easier comparisons.

@abirchfield, please check and merge into your branch.