Fix: support FormData object on fetch body

[bholmesdev]

Changes

• Resolves 🐛 BUG: FormData object causes fetch error #2741
• Move node-fetch to external dependency for @astrojs/webapi bundle. This was causing strange issues with body parsing that I still haven't figured out. Still, since @astrojs/telemetry already pulls in node-fetch as a standard dependency, this shouldn't be a problem!
• moving away from using node-fetch/src/index.js exposed type issues. A few pieces to resolve:
  • fetch no longer accepts URL as a resource type. Funny enough, you can still pass a URL for node-fetch to run toString() implicitly. Still, you get red squigglies in VS Code using URL today, so removing this type option is for consistency if anything.
  • FetchInit now uses node-fetch's body type in its type signature

Why not switch to undici like all the cool kids?

@FredKSchott (a cool kid) suggested using undici since it mirrors Node's incoming fetch standard. This seemed possible at first... until I discovered their node versioning requirements. In short: they don't expose fetch or Request for node versions below 16.5. Also poked the source code to confirm. This would mean dropping Node 14.X support, which feels a bit too far as we approach 1.0. Keep it in mind for the future though!

Testing

N/A

Docs

N/A

[matthewp]

lgtm

[changeset-bot]

🦋 Changeset detected

Latest commit: 3174bde

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 6 packages

Name	Type
@astrojs/webapi	Minor
astro	Patch
@astrojs/netlify	Patch
@astrojs/node	Patch
@astrojs/vercel	Patch
astro-scripts	Patch

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[natemoo-re]

LGTM! I would change the changeset to minor for webapi though.