Function mfp_to_safe_plan

fn mfp_to_safe_plan(
    mfp: MapFilterProject,
) -> Result<SafeMfpPlan, OptimizerError>

Convert mfp to an executable, non-temporal plan. It should be non-temporal, as OneShot preparation populates mz_now.

If the mfp can’t be converted into a non-temporal plan, this returns an internal error.