feat: Add reference thermal conductivity

[dkachuma]

Adds a reference thermal conductivity. The point of this is that the user might want this to be read from the vtk file for example. So we separate this from the effective thermal conductivity which is the calculated output from the thermal conductivity model.

#3956

Rebaseline to fix errors of type

********************************************************************************
Error: /Problem/domain/MeshBodies/mesh1/meshLevels/Level0/ElementRegions/elementRegionsGroup/region/elementSubRegions/cb
	Group has a child 'thermalCond_linear_referenceThermalConductivity' in the file to compare but not the baseline file.
********************************************************************************

which is expected because this change introduces this new wrapper.

[codecov]

Codecov Report

❌ Patch coverage is 63.15789% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.89%. Comparing base (5abf149) to head (8513525).

Files with missing lines	Patch %	Lines
...malConductivity/SinglePhaseThermalConductivity.cpp	84.00%	4 Missing ⚠️
...ers/surfaceGeneration/EmbeddedSurfaceGenerator.cpp	0.00%	4 Missing ⚠️
...sicsSolvers/surfaceGeneration/SurfaceGenerator.cpp	0.00%	4 Missing ⚠️
...onductivity/SinglePhaseThermalConductivityBase.cpp	50.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3959      +/-   ##
===========================================
- Coverage    58.89%   58.89%   -0.01%     
===========================================
  Files         1353     1353              
  Lines       113035   113065      +30     
===========================================
+ Hits         66573    66589      +16     
- Misses       46462    46476      +14     

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[OmarDuran]

@dkachuma thank you for your contribution. The modifications in the SurfaceGenerators look good.