feat: implement pool() for controlled concurrency and add tests #1375

[mariam851]

Fixes #1375

Added a pool() utility to manage parallel task execution with a strict concurrency limit. This is useful for rate-limiting operations or managing system resources during heavy async workloads.

Implementation:

Logic added to src/core.ts.

Uses a worker-queue pattern to ensure no more than limit tasks run simultaneously.

Accepts any Iterable of task-returning functions.

Testing: Verified on Windows 11. A test case with 4 tasks (1s each) and a limit of 2 finished in ~2.1s, confirming that tasks are queued correctly rather than running all at once or purely sequentially.

Added unit test in test/pool.test.js.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[antonmedv]

@antongolub I think we need to have a good understanding of pool() API before we can go on with a solution.