Convert constraints.f90 to Python

[timothy-nunn]

Description

Converts constraint_equations.f90 to Python.

Notes

• I have decided not to convert the additional debugging functions. These can be done by users as required. I only implemented NaN/inf checking on the cc

  PROCESS/source/fortran/constraint_equations.f90

  Lines 311 to 325 in 590cbb6

  	if (isnan(cc(i)).or.(abs(cc(i))>9.99D99)) then
  	! Add debugging lines as appropriate...
  	select case (icc(i))
  	! Relationship between beta, temperature (keV) and density (consistency equation)
  	case (1); call constraint_err_001()
  	! Equation for net electric power lower limit
  	case (16); call constraint_err_016()
  	! Equation for injection power upper limit
  	case (30); call constraint_err_030()
  	! Limit on rate of change of energy in poloidal field
  	case (66); call constraint_err_066()
  	end select

• I could not/did not want to replicate this weird logic of constraint 15

  PROCESS/source/fortran/constraint_equations.f90

  Lines 981 to 985 in 302cff7

  	if (fl_h_threshold > 1.0D0) then
  	tmp_symbol = '>'
  	else
  	tmp_symbol = '<'
  	end if

  so I have signed it as >= because it follows the form of other equations with that sign.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 52.16638% with 276 lines in your changes missing coverage. Please review.
✅ Project coverage is 37.40%. Comparing base (c100264) to head (f6d742d).
⚠️ Report is 387 commits behind head on main.

Files with missing lines	Patch %	Lines
process/constraints.py	51.85%	273 Missing ⚠️
process/final.py	33.33%	2 Missing ⚠️
process/caller.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3630      +/-   ##
==========================================
+ Coverage   37.01%   37.40%   +0.39%     
==========================================
  Files          84       85       +1     
  Lines       21679    22250     +571     
==========================================
+ Hits         8024     8323     +299     
- Misses      13655    13927     +272     

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[jonmaddock]

This is a great step, but I'm not totally convinced about the additional complexity of the decorator-based registration idea. What's the advantage of this approach?

[jonmaddock]

Thanks for explaining your approach, I'm happy with this now. Could you add docstrings to your new classes please, and find if there are any "adding a new constraint" docs which are now out of date. Could you deal with my minor "returning an array" comment, and lastly change cc and others to something more descriptive?