Add function to acquire random resource lock from a pool

[marvinhagemeister]

This PR adds a new function that acquires a random lock from a pool of resources.

const pool = ['A', 'B', 'C'];
const [lock1, lock2] = await acquireFromPool(config, pool, 2);

[marvinhagemeister]

Just got confirmation that the locking api isn't considered public yet. So I can do more drastic changes and make the API a little easier to use. Will split this work into multiple PRs.