fix: fetch support compressed responses

[mikicho]

fixes #2397 (comment)

This is a pretty naive solution that doesn't support more decoders easily (or multiple decoders at all), but I'm not expecting it in streams and such.
Improvements are welcome.

[Uzlopak]

What about deflate and co?

[mikicho]

@Uzlopak I can add support for deflate and br(?), but in this ugly(?) if/else style, it would be complex to support all combinations (it's possible to have more than one compression)
Do you have any ideas on how we can use streams? I tried to do something like:

const decoder = []
const codings = message.headers['content-encoding'].split(',')
for (const coding in codings) {
  if (coding === 'gzip') decoder.push(zlib.createGunzip())
  if (coding === 'deflate') decoder.push(..)
}

new ReadableStream({
  start(controller) {
    message.on('data', chunk => pipeline(Readable.from(chunk), ...decoders. () => {})
  }
})

But I got an error. I'm not an expert in streams, and I'm clearly missing something.

[Uzlopak]

Maybe here you can get some clues how we do it in undici.

nodejs/undici#2650

[mikicho]

@Uzlopak Thanks! I succeed to make it work.
I piled up the chunks because this is cleaner(?) then create promises and await for them to complete.

[Uzlopak]

BEAUTIFUL

[github-actions]

🎉 This PR is included in version 14.0.0-beta.4 🎉

The release is available on:

• npm package (@beta dist-tag)
• GitHub release

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[Uzlopak]

teamwork makes the dream work

[mikicho]