Add sol upstream power

[chris-ashe]

This pull request introduces new calculations and documentation for the scrape-off layer (SOL) parallel energy flux and area, and integrates them into the codebase and output. It also adds new physics variables for total magnetic fields at the inboard and outboard midplane, updates plotting and output routines to include these, and improves the documentation with references and formulas.

Scrape-off layer parallel flux and area calculations:

• Added calculation of the upstream outboard SOL parallel area (a_plasma_outboard_sol_eich13_parallel) and parallel power flux (pflux_plasma_outboard_sol_eich13_parallel_mw) to ScrapeOffLayer, including a new method calculate_upstream_sol_outboard_parallel_area and corresponding unit test.
• Extended the output of ScrapeOffLayer to display the new SOL parallel area and flux values.

Magnetic field calculations and variables:

• Added new variables for total magnetic field at the inboard and outboard midplane (b_plasma_inboard_total, b_plasma_outboard_total) and their calculation in the main physics model.
• Updated output and plotting routines to display these new magnetic field values, including improved format and sectioning in output files.

Documentation updates:

• Added a new section to the SOL documentation explaining the parallel energy flux density, the parallel area formula, and referenced key literature. [1] [2]

These changes improve the physical fidelity of the SOL model, enhance the clarity and completeness of outputs, and provide better documentation for users and developers.## Description

Checklist

I confirm that I have completed the following checks:

• My changes follow the PROCESS style guide
• I have justified any large differences in the regression tests caused by this pull request in the comments.
• I have added new tests where appropriate for the changes I have made.
• If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
• If I have made documentation changes, I have checked they render correctly.
• I have added documentation for my change, if appropriate.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 42.85714% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 49.14%. Comparing base (75f8468) to head (516b8a4).

Files with missing lines	Patch %	Lines
process/models/physics/scrape_off_layer.py	33.33%	8 Missing ⚠️
process/models/physics/plasma_fields.py	0.00%	5 Missing ⚠️
process/models/physics/physics.py	0.00%	2 Missing ⚠️
process/core/io/plot/summary.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4504      +/-   ##
==========================================
- Coverage   49.14%   49.14%   -0.01%     
==========================================
  Files         152      152              
  Lines       29777    29803      +26     
==========================================
+ Hits        14635    14647      +12     
- Misses      15142    15156      +14     

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[kj5248]

Think you made a slight mistake for the equation for parallel area

[kj5248]

Seems all good now

[clmould]

Some v minor changes but otherwise all good !