feat: support Bun

[AriPerkkio]

Related to vitest-dev/vitest#4111

• node:worker_threads are unstable on Bun and crash under heavy load
• node:worker_threads get stuck on Bun if there are while(true) {} loops inside the worker
• Bun's Workers are unstable, leak memory and crash under heavy load
• Bun does not open MessagePorts automatically, port.start() must be called manually
• Bun does not start node:child_process immediately like NodeJS does. It also does not emit spawn event. Manual work-arounds are required.

# Test how fast NodeJS can spin up and tear down 5000 worker_threads, 8 at a time on 8-CPU machine
$ node isolate-benchmark.mjs --threads 7 --rounds 5000
Options: { THREADS: 7, ROUNDS: 5000, IS_BUN: false } 

Native node:worker_threads | START
Native node:worker_threads | END   24622 ms

# Test how fast Bun can spin up and tear down 5000 Workers, 8 at a time on 8-CPU machine
$ bun isolate-benchmark.mjs --threads 7 --rounds 5000
Options: {
  THREADS: 7,
  ROUNDS: 5000,
  IS_BUN: true
} 

Native Bun workers | START
FATAL ERROR: JavaScript garbage collection failed because thread_get_state returned an error (268435459). This is probably the result of running inside Rosetta, which is not supported.
/Users/jarred/actions-runner/_work/WebKit/WebKit/Source/WTF/wtf/posix/ThreadingPOSIX.cpp(497) : size_t WTF::Thread::getRegisters(const WTF::ThreadSuspendLocker &, WTF::PlatformRegisters &)

Sometimes Bun crashes with libc++abi: Pure virtual function called! Abort trap: 6 error.

[AriPerkkio]

Workers are unable to terminate when using bun. I think the while loops below are causing it. oven-sh/bun#4134

import { isMainThread, Worker } from "node:worker_threads";
import { fileURLToPath } from "node:url";

if (isMainThread) {
  console.log("[main] running");
  const worker = new Worker(fileURLToPath(import.meta.url));

  await new Promise((r) => setTimeout(r, 1_000));
  const timeout = setTimeout(() => console.error("Timeout"), 2_000);

  console.log("[main] terminating");
  await worker.terminate();
  clearTimeout(timeout);
  console.log("[main] terminated");
} else {
  console.log("[worker] running");

  while (true) {}
}

ari ~/repro  $ node worker-threads.mjs 
[main] running
[worker] running
[main] terminating
[main] terminated

ari ~/repro  $ bun worker-threads.mjs 
[main] running
[worker] running
[main] terminating
Timeout
<stuck here>

[AriPerkkio]

Let's wait for fixes from Bun before moving on. Adding work-arounds just for Bun doesn't feel right.

oven-sh/bun#5709

[AriPerkkio]

Adding Bun support for Node APIs like node:worker_threads and node:child_process is not fun. I would not want to add Bun related work-arounds that affect Node users.

Let's instead add support for Bun's native Worker: #73