Split Smoother Matrix Construction into Separate COO and Tridiagonal Sections

[julianlitz]

Merge Request - GuideLine Checklist

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• Tests for new functionality has been added
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[julianlitz]

@EmilyBourne I removed the Residual and DirectSolver changes.
I think it cant really be simplified further into multiple PRs...
You can mostly ignore the new parallelization approach since

1. We will do it differently with Kokkos nevertheless
2. I can assure you this new way is a lot better and works the same

Note that the Smoother Give is very well tested against the Take counter part.
If a single matrix entry is not the same, the tests will fails immediately.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.02%. Comparing base (85dfe79) to head (f7acf51).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #246      +/-   ##
==========================================
- Coverage   90.10%   90.02%   -0.08%     
==========================================
  Files          80       79       -1     
  Lines        8854     8706     -148     
==========================================
- Hits         7978     7838     -140     
+ Misses        876      868       -8     

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[EmilyBourne]

@julianlitz I merged #247 . Can you fix the merge conflicts that this has created

[julianlitz]

🫠 Oki

[julianlitz]

@EmilyBourne Conflicts resolved