Eliminates circular dependency on timer modules.

[mo36924]

Describe the feature

The timers/promises module has circular dependency.

The following warning is output when building with rollup.
(!) Circular dependency
node_modules/unenv/runtime/node/timers/promises/index.mjs -> node_modules/unenv/runtime/node/timers/internal/scheduler.mjs -> node_modules/unenv/runtime/node/timers/promises/index.mjs

unenv/src/runtime/node/timers/internal/scheduler.ts

Line 2 in ada7c40

import { setTimeout, setImmediate } from "node:timers/promises";

I think this problem can be solved by modifying the above as follows.

import { setTimeoutFallbackPromises as setTimeout } from "./set-timeout";
import { setImmediateFallbackPromises as setImmediate } from "./set-immediate";

Additional information

• Would you be willing to help implement this feature?