Move the promisified timers implementations into a new experimental
sub-module to avoid the need to promisify. The promisified versions
now return the timers/promises versions.

Also adds ref option to the promisified versions

const {
  setTimeout,
  setImmediate
} = require('timers/promises');

setTimeout(10, null, { ref: false })
  .then(console.log);

setImmediate(null, { ref: false })
  .then(console.log);

// The promisify versions of the original timers return the same functions...
const timers = require('timers');
const { promisify } = require('util');
const assert = require('assert');

assert.strictEqual(promisify(timers.setTimeout), setTimeout);
assert.strictEqual(promisify(timers.setImmediate), setImmediate);

Needs the additional fixes implemented in #33949 ... this one is blocked on that one landing.

Signed-off-by: James M Snell jasnell@gmail.com

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines