Create up down div classes

[chris-ashe]

This pull request refactors the blanket and divertor modules to improve code modularity, reusability, and clarity. Key changes include separating inboard and outboard blanket geometry logic into dedicated classes, generalizing the calculation of pumping powers, and unifying the computation of divertor incident powers into reusable methods. These changes enable more maintainable and extensible blanket and divertor models across the codebase.

Blanket geometry and modularization:

• Introduced InboardBlanket and OutboardBlanket classes in blanket_library.py, each encapsulating their respective geometry calculations and segment length methods, replacing direct calculations in the old BlanketLibrary class.
• Updated DCLL and CCFE_HCPB blanket models to inherit from the new InboardBlanket and OutboardBlanket classes, and refactored their run methods to use the new geometry calculation methods for setting segment lengths.
• Removed direct toroidal segment length calculations from set_blanket_module_geometry in favor of the new modular methods.

Pumping power calculation improvements:

• Refactored set_pumping_powers_as_fractions to accept all required parameters as arguments and return a tuple of results, improving testability and reusability. Updated all blanket models to use the new function signature.

Divertor power calculation refactor:

• Centralized the calculation of incident neutron and radiation power on the divertor into new methods (set_incident_neutron_power, set_incident_radiation_power) in Divertor, and updated the divertor and blanket models to use these methods instead of duplicating logic.
  Class structure and code organization:

• Added empty LowerDivertor and UpperDivertor classes as placeholders for future specialization, inheriting from the refactored Divertor class.

These changes collectively enhance the maintainability, clarity, and extensibility of the blanket and divertor modelling code.## 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 77.77778% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.88%. Comparing base (2f754a2) to head (426bc22).

Files with missing lines	Patch %	Lines
process/divertor.py	77.77%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3999      +/-   ##
==========================================
- Coverage   45.88%   45.88%   -0.01%     
==========================================
  Files         123      123              
  Lines       29087    29082       -5     
==========================================
- Hits        13346    13343       -3     
+ Misses      15741    15739       -2     

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[timothy-nunn]

Before I review can you merge #3997 and then rebase this PR onto main

[timothy-nunn]

Happy with these changes. They are stepping stones towards having separate upper and lower divertor models which will be a great addition to PROCESS.