feat(interval): option to unref sleep interval

[jeengbe]

Normally, this is not a problem, however when using bufferCountOrTime() in unit tests, Jest tends to hang due to the interval used in sleep().

Demo:

test('x', async () => {
  // Use a longer interval than the Jest timeout to demonstrate "Jest did not exit one second after the test run has completed."
  await from([]).pipe(bufferCountOrTime(0, 10000)).forEach(console.log);
});

This PR adds an optional unref: boolean parameters that default to the current behaviour. I think it makes sense to unref only in bufferCountOrTime() and timeout().

There are currently not really tests for any of the affected files. I would defer coverage of more operators for another PR, if that is okay.

[jeengbe]

The UMD code this gives looks very suspicious, specifically the h.Fa() which should stay h.unref(). (How) is this intended?

function vb(a, b, c) {
    c = void 0 === c ? !1 : c;
    return new Promise(function (e, d) {
        function f() {
            clearTimeout(h);
            d(new R());
        }
        b && b.aborted && d(new R());
        var h = setTimeout(function () {
            if (b && (b.removeEventListener("abort", f), b.aborted)) {
                f();
                return;
            }
            e();
        }, a);
        c && "unref" in h && h.Fa();
        b && b.addEventListener("abort", f, { once: !0 });
    });
}

[trxcllnt]

id.unref() is getting mangled by closure compiler, change it to id['unref']() and it won't get mangled.

[jeengbe]

Aha, that's the reason for all the

const { ['signal']: signal, ['thisArg']: thisArg, ['predicate']: predicate } = options

Strange that it does that, but thanks, makes sense. Fixed the PR.