Function execute_chunked 

pub async fn execute_chunked<T, I, F, Fut>(
    items: I,
    chunk_size: usize,
    max_concurrency: usize,
    operation: F,
) -> Vec<Vec<Result<T, String>>>
where
    I: IntoIterator,
    I::IntoIter: ExactSizeIterator,
    F: Fn(Vec<I::Item>) -> Fut + Clone + Send + 'static,
    Fut: Future<Output = Vec<Result<T, String>>> + Send + 'static,
    T: Send + 'static,
    I::Item: Send + Clone + 'static,

Execute operations in parallel chunks.

Useful for operations that benefit from batching (like multi-row inserts) combined with parallel execution of batches.