Function concrete_npe::cross::bootstrap_then_key_switch

pub fn bootstrap_then_key_switch(
    n: usize, 
    l_bsk: usize, 
    log_base_bsk: usize, 
    stdev_bsk: f64, 
    polynomial_size: usize, 
    l_ks: usize, 
    log_base_ks: usize, 
    stdev_ks: f64
) -> f64