InternalEnergyFromDensityPressure

[Yurlungur]

PR Summary

As requested by @rbberger for Ristra, I add here a method for InternalEnergyFromDensityPressure. This method ports into singularity-eos the same machinery used by Phoebus and riot (hence why I ping @AstroBarker, @pdmullen , and @jdolence ). Going forward, this will reduce code duplication as those downstream codes will no longer need to implement the method themselves.

PR Checklist

• Adds a test for any bugs fixed. Adds tests for new features.
• Format your changes by using the make format command after configuring with cmake.
• Document any new features, update documentation for changes made.
• Make sure the copyright notice on any files you modified is up to date.
• After creating a pull request, note it in the CHANGELOG.md file.
• LANL employees: make sure tests pass both on the github CI and on the Darwin CI

If preparing for a new release, in addition please check the following:

• Update the version in cmake.
• Move the changes in the CHANGELOG.md file under a new header for the new release, and reset the categories.
• Ensure that any when='@main' dependencies are updated to the release version in the package.py

[Yurlungur]

Note a few things:

• This is out of sync with @rbberger 's update that pulls in ports-of-call/variant
• I did add the vector calls, but I did not add the Python calls or a performant EOSPAC call. Those are TODOs, though I expect both are desirable, especially as riot moves towards python-based initial conditions.

[Yurlungur]

I believe this is ready for review no. Thanks @rbberger ! @adamdempsey90 can you take a look?

[Yurlungur]

@rbberger do you want to merge this? Or should we hold off still?

[rbberger]

@Yurlungur I would say go for it. If we need more I'll reach out next year.