Refactor SurfaceIntegral to make it 3D ready

[DanielDoehring]

Similar to many other files this PR splits the analysis_surface_integral_2d.jl files into a dimension-general/independent one analysis_surface_integral.jl and a 2D specialized one analysis_surface_integral_2d.jl. Should make extension to 3D simpler.

[github-actions]

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[codecov]

Codecov Report

Attention: Patch coverage is 80.95238% with 12 lines in your changes missing coverage. Please review.

Project coverage is 96.94%. Comparing base (6a1f16d) to head (57c3cfe).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/callbacks_step/analysis_surface_integral.jl	70.00%	12 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2375   +/-   ##
=======================================
  Coverage   96.94%   96.94%           
=======================================
  Files         503      504    +1     
  Lines       41717    41717           
=======================================
  Hits        40440    40440           
  Misses       1277     1277           

Flag	Coverage Δ
unittests	96.94% <80.95%> (ø)

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[ranocha]

Thanks a lot!

[ranocha]

Thanks!