Add MPhys builder options for residual scaling and solution writing

[A-CGray]

Purpose

Adds two new options to the ADflowBuilder class:

• write_solution to allow disabling of automatic solution file writing
• res_ref to specify a reference residual value that will be used by OpenMDAO to scale the residual

Warning: as explained in OpenMDAO/OpenMDAO#3072 OpenMDAO doesn't currently apply the residual scaling correctly to matrix-free partial derivatives, so any check_partials currently fails if you do any residual scaling. The total derivatives are fine though.

ToDo before merging

• Merge add get_tagged_indices method to ADflowBuilder #298
• Add description for balance_group builder argument

Expected time until merged

Type of change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

Testing

Checklist

• I have run flake8 and black to make sure the Python code adheres to PEP-8 and is consistently formatted
• I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• I have run unit and regression tests which pass locally with my changes
• I have added new tests that prove my fix is effective or that my feature works
• I have added necessary documentation

[codecov]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (a587798) 41.52% compared to head (eabaf88) 41.46%.

Files	Patch %	Lines
adflow/mphys/mphys_adflow.py	0.00%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #332      +/-   ##
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- Coverage   41.52%   41.46%   -0.07%     
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  Files          13       13              
  Lines        4058     4064       +6     
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  Hits         1685     1685              
- Misses       2373     2379       +6     

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[A-CGray]

@ArshSaja @anilyil @lamkina can one of you fill out the description of the balance_group input in the ADflowBuilder docstring?

[A-CGray]

@lamkina this PR is waiting on someone to address my comment above, and then for #298 to be merged

[A-CGray]

@lamkina, @anilyil or @ArshSaja , can one of you write a description for this balance group argument, I don't know what it does but I'm assuming it's something to do with aeropropulsive cases

[A-CGray]

This is good to go now I believe

[lamkina]

This looks good to me. Doesn't touch anything outside of the residual scaling so nicely contained. LGTM