Function set_exec_params 

pub fn set_exec_params(
    graph: &CudaGraph,
    node: CUgraphNode,
    params: &CUDA_KERNEL_NODE_PARAMS,
) -> Result<(), Box<dyn Error>>

Push updated launch params for one node into the instantiated exec. params is the (edited) struct from kernel_nodes — same node topology, new geometry/arg values.