Refactor PsVecHorizontal as PsBinOp

src/pystencils/backend/ast/vector.py

src/pystencils/backend/emission/ir_printer.py

src/pystencils/backend/kernelcreation/typification.py

src/pystencils/backend/platforms/x86.py

src/pystencils/backend/transformations/loop_vectorizer.py

src/pystencils/backend/transformations/select_intrinsics.py

src/pystencils/include/simd_horizontal_helpers.h