[chore] Make rawBody be the bytes

[JeanJPNM]

Before submitting the PR, please make sure you do the following

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

Changesets

• If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpx changeset and following the prompts. All changesets should be patch until SvelteKit 1.0

Closes #1893 by ensuring rawBody is an Uint8Array before it is passed down to request handlers.

[changeset-bot]

🦋 Changeset detected

Latest commit: bedda81

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

This PR includes changesets to release 3 packages

Name	Type
@sveltejs/adapter-cloudflare-workers	Patch
@sveltejs/adapter-netlify	Patch
@sveltejs/kit	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[Rich-Harris]

thank you! i may not have fully understood everything, but it feels like we can simplify even further? comments inline

[Rich-Harris]

thanks for those changes. i had one final question (see comments) then i think this is probably good to go

[Rich-Harris]

this change is a huge improvement — thank you!