begin migration to native fetch()

[cjihrig]

Refs: #2306

A few notes:

• This unblocks the nock update. In fact, I believe it necessitates the update because the older nock version didn't seem to support native fetch.
• There is future room for improvement related to the use of web streams. Native fetch uses web streams, while node-fetch uses Node streams. Just to get this migration going, I used a conversion function (search the diff for Readable.fromWeb()), but ideally we would try working with web streams directly to reduce some overhead.
• node-fetch is still used in src/gen/http/isomorphic-fetch.ts, which I think would need to be resolved in the code generator.
• In src/util.ts, there is a normalizeResponseHeaders() that apparently exists due to a node-fetch quirk. I did not look into whether or not that is still needed, but keeping it doesn't seem to break anything.
• FetchError does not appear to be a thing in native fetch.

We may or may not want to keep this as a draft PR because of this list and pending the CI - what do others think?

[mstruebing]

That's pretty cool already!

I don't think Readable.fromWeb() is that bad actually, sure a little bit of overhead but nothing serious.
I had a quick look into the code gen but I'm a bit overwhelmed right now.
Not sure if we can adjust the current gen code or if we would need a different/new one, as we are using a different fetching library.

[cjihrig]

My guess is that we'd need a different code generator (or at least new capabilities in the existing one) since there are enough small, subtle differences between node-fetch and native fetch.

[brendandburns]

Looks good to me, my only question is for the package-lock.json there's a lot of additional dependencies that seem kind of random. Is that all really from the nock upgrade?

[cjihrig]

Is that all really from the nock upgrade?

As far as I can tell, yes. The joys of depending on things from npm. nock started depending on @mswjs/interceptors (this is the thing that broke our tests), which brings in its own dependencies, like jsdom. You can verify any of them like this:

$ npm ls @asamuzakjp/css-color
@kubernetes/[email protected] /Users/cjihrig/programming/javascript
└─┬ [email protected]
  └─┬ @mswjs/[email protected]
    └─┬ [email protected]
      └─┬ [email protected]
        └── @asamuzakjp/[email protected]

[cjihrig]

You can also check out this dependabot PR from last night that tried to make the same update - #2337.

[brendandburns]

/lgtm
/approve

Thanks.

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