🏗️ Remove SolverFactory to entirely isolate NALAC

[ystade]

Description

NASP had still a dependency on NALAC. The only part where this was used was the solver factory. Sine this was not super useful anyways, the solver factory is removed together with the dependency on NALAC.

Checklist:

• The pull request only contains commits that are related to it.
• I have added appropriate tests and documentation.
• I have made sure that all CI jobs on GitHub pass.
• The pull request introduces no new warnings and follows the project's style guidelines.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.0%. Comparing base (f56efbf) to head (ece67e9).
Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #609     +/-   ##
=======================================
- Coverage   91.1%   91.0%   -0.1%     
=======================================
  Files        104     103      -1     
  Lines      10932   10900     -32     
  Branches    1862    1861      -1     
=======================================
- Hits        9960    9928     -32     
  Misses       972     972             

Flag	Coverage Δ
cpp	90.8% <100.0%> (-0.1%)	⬇️
python	96.5% <ø> (+<0.1%)	⬆️

Files with missing lines	Coverage Δ
include/na/nasp/Solver.hpp	95.0% <ø> (ø)
src/na/nasp/Solver.cpp	93.9% <100.0%> (+0.2%)	⬆️

... and 3 files with indirect coverage changes

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[burgholzer]

Just two tiny comments about the include style.

And it would be nice to get that codecov check green, if easily possible.