Make --watch instant

[Jarred-Sumner]

What does this PR do?

This makes --watch not wait on the event loop. So if you have slow code that is running, the script restarts immediately instead of waits. While we do use CLOEXEC, we also go ahead and manually track open listening sockets for the HTTP server and close them all before reloading the process. I think that was the original reason why we didn't do this - because you could end up in situations where the OS would route it to a stale HTTP server listening.

How did you verify your code works?

Manual + existing tests

[github-actions]

❌ @Jarred-Sumner 2 files with test failures on linux-x64:

• test/bundler/esbuild/splitting.test.ts
• test/js/web/fetch/fetch-gzip.test.ts

View test output

^{#f569551671f7cab6066e9a27c3abb0a4eea8a8e3}

[github-actions]

❌ @Jarred-Sumner 6 files with test failures on bun-darwin-x64-baseline:

• test/cli/install/bun-install.test.ts
• test/js/bun/spawn/spawn-streaming-stdout.test.ts
• test/js/bun/sqlite/sqlite.test.js
• test/js/node/fs/fs.test.ts
• test/js/third_party/webpack/webpack.test.ts
• test/js/web/timers/setTimeout.test.js

View test output

^{#f569551671f7cab6066e9a27c3abb0a4eea8a8e3}