Specify type of Newton's Method within .cfg file for 2T in M++

[aaronmlarsen]

Proposed Changes

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Using .cfg file, you can specify to use M++'s 2T temperature calculation using h/cp or to use a finite difference perturbation method to solve for the Jacobian.

Related Work

Resolve any issues (bug fix or feature request), note any related PRs, or mention interactions with the work of others, if any.

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• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with --warnlevel=3 when using meson).
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• I used the pre-commit hook to prevent dirty commits and used pre-commit run --all to format old commits.
• I have added a test case that demonstrates my contribution, if necessary.
• I have updated appropriate documentation (Tutorials, Docs Page, config_template.cpp), if necessary.