fix various typos

Eigen/src/Core/ArrayBase.h

Eigen/src/Core/DenseCoeffsBase.h

Eigen/src/Core/ProductEvaluators.h

Eigen/src/Core/Ref.h

Eigen/src/Core/arch/Default/Half.h

Eigen/src/Core/arch/SSE/PacketMath.h

Eigen/src/Core/arch/SYCL/SyclMemoryModel.h

Eigen/src/Core/functors/BinaryFunctors.h

Eigen/src/Core/functors/UnaryFunctors.h

Eigen/src/Core/products/GeneralBlockPanelKernel.h

Eigen/src/Core/products/GeneralMatrixVector.h

Eigen/src/Core/util/Macros.h

Eigen/src/Core/util/Serializer.h

Eigen/src/Eigenvalues/ComplexSchur.h

Eigen/src/SVD/SVDBase.h

Eigen/src/SparseCore/SparseBlock.h

Eigen/src/plugins/CommonCwiseBinaryOps.h

cmake/EigenTesting.cmake

cmake/FindComputeCpp.cmake

doc/PreprocessorDirectives.dox