Fixes#128071
The current behavior lets intrinsics that don't map to a DXILOP slip
through. Nothing catches this until we hit the DXIL validator. This
change fails earlier so we don't encode invalid llvm intrinsics that can
slip through because of clang builtins like `__builtin_reduce_and`
example:
https://hlsl.godbolt.org/z/13rPj18vn