Make KLEIDICV_NEON_USE_CONTINUOUS_MULTIVEC_LS a CMake option
To make it possible to drive those code paths from CI script. So far setting -DKLEIDICV_NEON_USE_CONTINUOUS_MULTIVEC_LS=OFF in scripts/ci.sh had no effect.
CMake comment KLEIDICV_NEON_USE_CONTINUOUS_MULTIVEC_LS is also updated to match with the implementation.