Replace the CVTTPD2DQ/CVTTPD2UDQ and CVTDQ2PD/CVTUDQ2PD opcodes with general versions.
This is an initial step towards similar FP_TO_SINT/FP_TO_UINT and SINT_TO_FP/UINT_TO_FP lowering to AVX512 CVTTPS2QQ/CVTTPS2UQQ and CVTQQ2PS/CVTUQQ2PS with illegal types.