Move Core unit tests in C++ files

Tests/UnitTests/Core/Sample/CrystalTest.cpp

Tests/UnitTests/Core/Sample/FormFactorBasicTest.cpp

Tests/UnitTests/Core/Sample/FormFactorCoherentSumTest.cpp

Tests/UnitTests/Core/Sample/FormFactorSoftParticleTest.cpp

Tests/UnitTests/Core/Sample/INodeTest.cpp

Tests/UnitTests/Core/Sample/Lattice2DTest.cpp

Tests/UnitTests/Core/Sample/LatticeTest.cpp

Tests/UnitTests/Core/Sample/LatticeUtilsTest.cpp

Tests/UnitTests/Core/Sample/LayerInterfaceTest.cpp

Tests/UnitTests/Core/Sample/LayerRoughnessTest.cpp

Tests/UnitTests/Core/Sample/LayerTest.cpp

Tests/UnitTests/Core/Sample/MesoCrystalTest.cpp

Tests/UnitTests/Core/Sample/MultiLayerTest.cpp

Tests/UnitTests/Core/Sample/ParticleCompositionTest.cpp

Tests/UnitTests/Core/Sample/ParticleCoreShellTest.cpp

Tests/UnitTests/Core/Sample/ParticleDistributionTest.cpp

Tests/UnitTests/Core/Sample/ParticleLayoutTest.cpp

Tests/UnitTests/Core/Sample/ParticleTest.cpp

Tests/UnitTests/Core/Sample/RTTest.cpp

Tests/UnitTests/Core/Sample/testlist.h