Fixed getType to be consistent across different matrix formats.

src/TNL/Matrices/AdEllpack_impl.h

src/TNL/Matrices/BiEllpackSymmetric_impl.h

src/TNL/Matrices/BiEllpack_impl.h

src/TNL/Matrices/COOMatrix_impl.h

src/TNL/Matrices/CSR_impl.h

src/TNL/Matrices/ChunkedEllpack_impl.h

src/TNL/Matrices/Dense_impl.h

src/TNL/Matrices/EllpackSymmetricGraph_impl.h

src/TNL/Matrices/EllpackSymmetric_impl.h

src/TNL/Matrices/Ellpack_impl.h

src/TNL/Matrices/Multidiagonal_impl.h

src/TNL/Matrices/SlicedEllpackSymmetricGraph_impl.h

src/TNL/Matrices/SlicedEllpackSymmetric_impl.h

src/TNL/Matrices/SlicedEllpack_impl.h

src/TNL/Matrices/Tridiagonal_impl.h