Moved simple unit converters to a separate h/cpp files

Core/Instrument/SimpleUnitConverters.cpp

Core/Instrument/SimpleUnitConverters.h

Core/Instrument/SimulationResult.h

Core/Instrument/UnitConverters.cpp

Core/Instrument/UnitConverters.h

Core/Simulation/GISASSimulation.cpp

Core/Simulation/OffSpecSimulation.cpp

Core/Simulation/SpecularSimulation.cpp

Tests/UnitTests/Core/Detector/OffSpecularConverterTest.h

Tests/UnitTests/Core/Detector/RectangularConverterTest.h

Tests/UnitTests/Core/Detector/SphericalConverterTest.h