[WIP] pywrapper - custom source terms for all solvers

[bigfooted]

Proposed Changes

Introduce custom source terms for all solvers through the python wrapper.

• reproduces the laminar buoyancy driven cavity testcase
• can simulate a turbulent premixed flame using turbulent flamespeed closure (TFC)

PR Checklist

Put an X by all that apply. You can fill this out after submitting the PR. If you have any questions, don't hesitate to ask! We want to help. These are a guide for you to know what the reviewers will be looking for in your contribution.

• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with --warnlevel=3 when using meson).
• My contribution is commented and consistent with SU2 style (https://su2code.github.io/docs_v7/Style-Guide/).
• 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.

The best way to fix the problem is to remove the assignment of the nElem variable since it is not used anywhere in the code. This will clean up the code and eliminate the unnecessary variable. The change should be made in the main function of the TestCases/py_wrapper/custom_source/run.py file.

The best way to fix the problem is to remove the assignment of the unused variable index_Vel. This will clean up the code and remove any potential confusion about the purpose of the variable. Since the right-hand side of the assignment does not have any side effects, it is safe to remove the entire line.

The best way to fix the problem is to remove the assignment of the unused variable primindex. This will clean up the code and remove any potential confusion about the purpose of the variable. Since the right-hand side of the assignment does not have any side effects, it is safe to remove the entire line.

The best way to fix the problem is to remove the unused variable iDENSITY. Since the assignment of iDENSITY does not have any side effects, we can safely delete the entire line where iDENSITY is assigned. This will clean up the code and remove any potential confusion about the purpose of the variable.

The best way to fix the problem is to remove the assignment of the index_Vel variable since it is not used anywhere in the code. This will clean up the code and remove any potential confusion about the purpose of the variable.

To implement this fix, we need to delete the line where index_Vel is assigned a value. This change should be made in the file TestCases/py_wrapper/turbulent_premixed_psi/run.py on line 229.

To fix the problem, we need to remove the assignment of the custom_source_vector variable since it is not used anywhere in the code. This will clean up the code and eliminate the unnecessary variable. The change should be made in the file TestCases/py_wrapper/turbulent_premixed_psi/run.py on line 232.