added option pf case splitting

[billingsley-john]

Proposed changes

PR which begins to add option splitting to pf coil casings.

Types of changes

What types of changes does your code introduce to the Paramak?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Code refactoring
• Documentation Update (if none of the other choices apply)
• New tests

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• Pep8 applied
• Unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

TODO:

• update documentation

[codecov]

Codecov Report

Merging #848 (82ffd82) into develop (ddcfff3) will decrease coverage by 0.18%.
The diff coverage is 70.73%.

❗ Current head 82ffd82 differs from pull request most recent head 032fc09. Consider uploading reports for the commit 032fc09 to get more accurate results

@@             Coverage Diff             @@
##           develop     #848      +/-   ##
===========================================
- Coverage    94.68%   94.50%   -0.19%     
===========================================
  Files           75       75              
  Lines         5404     5443      +39     
===========================================
+ Hits          5117     5144      +27     
- Misses         287      299      +12     

Impacted Files	Coverage Δ
.../parametric_components/poloidal_field_coil_case.py	82.60% <70.73%> (-17.40%)	⬇️

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