Tests: split main functions into separate headers

src/UnitTests/AssertCudaTest.cu

src/UnitTests/AssertTest.cpp

src/UnitTests/Containers/ArrayOperationsTest.h

src/UnitTests/Containers/ArrayTest.h

src/UnitTests/Containers/ArrayViewTest.h

src/UnitTests/Containers/DistributedArrayTest.h

src/UnitTests/Containers/DistributedVectorTest.h

src/UnitTests/Containers/ListTest.cpp

src/UnitTests/Containers/Multimaps/MultimapTest.cpp

src/UnitTests/Containers/Multimaps/StaticMultimapTest.cpp

src/UnitTests/Containers/MultireductionTest.h

src/UnitTests/Containers/StaticArrayTest.cpp

src/UnitTests/Containers/StaticVectorTest.cpp

src/UnitTests/Containers/VectorTest.h

src/UnitTests/FileNameTest.cpp

src/UnitTests/FileTest.h

src/UnitTests/Functions/BoundaryMeshFunctionTest.h

src/UnitTests/Functions/MeshFunctionTest.h

src/UnitTests/Matrices/DenseMatrixTest.h

src/UnitTests/Matrices/DistributedMatrixTest.h