REsolve #2305 let two coilsets of diff parametrization be added together

[dpanici]

Resolves #2305

[github-actions]

Memory benchmark result

|               Test Name                |      %Δ      |    Master (MB)     |      PR (MB)       |    Δ (MB)    |    Time PR (s)     |  Time Master (s)   |
| -------------------------------------- | ------------ | ------------------ | ------------------ | ------------ | ------------------ | ------------------ |
  test_objective_jac_w7x                 |   -0.55 %    |     4.250e+03      |     4.226e+03      |    -23.52    |       30.95        |       28.54        |
  test_proximal_jac_w7x_with_eq_update   |   -0.44 %    |     6.851e+03      |     6.821e+03      |    -30.13    |       155.93       |       153.65       |
  test_proximal_freeb_jac                |    0.10 %    |     1.354e+04      |     1.355e+04      |    12.88     |       81.61        |       79.74        |
  test_proximal_freeb_jac_blocked        |   -0.24 %    |     7.891e+03      |     7.872e+03      |    -19.11    |       69.02        |       69.78        |
  test_proximal_freeb_jac_batched        |   -0.64 %    |     7.893e+03      |     7.842e+03      |    -50.20    |       68.37        |       70.54        |
  test_proximal_jac_ripple               |   -1.78 %    |     3.811e+03      |     3.743e+03      |    -67.83    |       53.73        |       54.46        |
  test_proximal_jac_ripple_bounce1d      |   -0.22 %    |     4.004e+03      |     3.995e+03      |    -8.75     |       67.13        |       69.39        |
  test_eq_solve                          |    0.20 %    |     1.821e+03      |     1.824e+03      |     3.58     |       53.46        |       54.36        |
  test_objective_quadratic_flux_jac      |    0.81 %    |     1.873e+03      |     1.888e+03      |    15.18     |       35.59        |       36.35        |

For the memory plots, go to the summary of Memory Benchmarks workflow and download the artifact.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.36%. Comparing base (187e98e) to head (b87e5f0).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2306      +/-   ##
==========================================
+ Coverage   94.34%   94.36%   +0.01%     
==========================================
  Files         101      101              
  Lines       29042    29046       +4     
==========================================
+ Hits        27400    27408       +8     
+ Misses       1642     1638       -4     

Files with missing lines	Coverage Δ
desc/coils.py	96.97% <100.00%> (+0.13%)	⬆️

... and 2 files with indirect coverage changes

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