Function execute_wave 

pub fn execute_wave<F>(wave: &Wave, execute_fn: F) -> Vec<WaveStepResult>
where
    F: Fn(&str) -> WaveStepResult + Send + Sync,

Execute a wave of steps in parallel using scoped threads.

The execute_fn closure is called once per step, receiving the step name. It must be Send + Sync since it runs across threads.

Returns results for all steps in the wave (order not guaranteed for parallel).