Implement a function mapAsyncLimit(array, asyncFn, limit) that maps over an array using an asynchronous function.

The function should:

• Accept an array of items.
• Accept an async mapping function that returns a promise.
• Optionally accept a limit for maximum concurrent operations. If no limit is provided, all items can be processed concurrently.
• Return a promise that resolves to an array of mapped results in the same order as the input array.

Examples

async function toUpper(str) {
  return str.toUpperCase();
}

await mapAsyncLimit(['a', 'b', 'c'], toUpper, 2); // ['A', 'B', 'C']