Add tf shape enum

[chris-ashe]

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 58.33333% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.63%. Comparing base (12afd93) to head (6aa33d0).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
process/models/tfcoil/base.py	53.84%	6 Missing ⚠️
process/core/init.py	60.00%	2 Missing ⚠️
process/core/io/plot_proc.py	50.00%	1 Missing ⚠️
process/models/pfcoil.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4130      +/-   ##
==========================================
- Coverage   47.91%   47.63%   -0.29%     
==========================================
  Files         142      142              
  Lines       29923    29970      +47     
==========================================
- Hits        14338    14276      -62     
- Misses      15585    15694     +109     

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[timothy-nunn]

I think it would be nice to replace all uses of testing (e.g. if i == 1) or setting using bare constants to be replaced. Here are some other locations this occurs:

• plot_proc.py
• build.py
• pfcoil.py
• tfcoil/base.py
• test_build.py

[timothy-nunn]

Just one question, I may just be being silly