Function emit_mma_tn_ldm_cfg_bench 

pub fn emit_mma_tn_ldm_cfg_bench(
    bm: usize,
    bn: usize,
    bk: usize,
    warps_m: usize,
    warps_n: usize,
    stages: usize,
    m: usize,
    k: usize,
    n: usize,
) -> String

Emit the ldmatrix+mma.sync.s8 TN kernel for a specific config so the frontier can sweep block/warp/stage shapes on-device. stages shared buffers (cp.async N-stage). WN must be a multiple of 8, WM of 16.