perf: avoid using raw-body for server actions

[feedthejim]

This PR removes the usage of raw-body for App Router pages by parsing the body for an action ourselves whilst assuming that it is encoded with UTF-8. This is already what we do for the Edge Runtime version of Server Actions and will only break if your page overrides the page encoding, which should not happen and that we don't need to support.

This should remove a third of a serverless function zip size

[ijjk]

Stats from current PR

Default Build

General

	vercel/next.js canary	vercel/next.js feedthejim/deprecate-raw-body	Change
buildDuration	10.3s	10.2s	N/A
buildDurationCached	5.9s	6s	N/A
nodeModulesSize	175 MB	175 MB	N/A
nextStartRea..uration (ms)	409ms	419ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js feedthejim/deprecate-raw-body	Change
199-HASH.js gzip	32.3 kB	32.3 kB	N/A
3f784ff6-HASH.js gzip	53.2 kB	53.2 kB	N/A
99.HASH.js gzip	182 B	182 B	✓
framework-HASH.js gzip	45.5 kB	45.5 kB	✓
main-app-HASH.js gzip	254 B	251 B	N/A
main-HASH.js gzip	35.3 kB	35.4 kB	N/A
webpack-HASH.js gzip	1.75 kB	1.75 kB	N/A
Overall change	45.7 kB	45.7 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js feedthejim/deprecate-raw-body	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js feedthejim/deprecate-raw-body	Change
_app-HASH.js gzip	206 B	205 B	N/A
_error-HASH.js gzip	182 B	180 B	N/A
amp-HASH.js gzip	506 B	505 B	N/A
css-HASH.js gzip	322 B	323 B	N/A
dynamic-HASH.js gzip	2.59 kB	2.59 kB	✓
edge-ssr-HASH.js gzip	260 B	259 B	N/A
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	369 B	369 B	✓
image-HASH.js gzip	4.38 kB	4.38 kB	N/A
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.67 kB	2.67 kB	N/A
routerDirect..HASH.js gzip	316 B	318 B	N/A
script-HASH.js gzip	385 B	384 B	N/A
withRouter-HASH.js gzip	319 B	319 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	3.99 kB	3.99 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js feedthejim/deprecate-raw-body	Change
_buildManifest.js gzip	484 B	482 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js feedthejim/deprecate-raw-body	Change
index.html gzip	528 B	531 B	N/A
link.html gzip	542 B	542 B	✓
withRouter.html gzip	524 B	524 B	✓
Overall change	1.07 kB	1.07 kB	✓

Edge SSR bundle Size

	vercel/next.js canary	vercel/next.js feedthejim/deprecate-raw-body	Change
edge-ssr.js gzip	96 kB	96 kB	✓
page.js gzip	139 kB	139 kB	N/A
Overall change	96 kB	96 kB	✓

Middleware size

	vercel/next.js canary	vercel/next.js feedthejim/deprecate-raw-body	Change
middleware-b..fest.js gzip	624 B	627 B	N/A
middleware-r..fest.js gzip	150 B	151 B	N/A
middleware.js gzip	25.8 kB	25.8 kB	N/A
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	1.92 kB	1.92 kB	✓

Commit: 1065597

[ijjk]

Failing test suites

Commit: 1065597

pnpm test-dev test/development/basic/next-rs-api.test.ts

• next.rs api > should allow to make many HMR updates

Expand output

● next.rs api › should allow to make many HMR updates

thrown: "Exceeded timeout of 300000 ms for a test.
Add a timeout value to this test to increase the timeout, if this is a long-running test. See https://jestjs.io/docs/api#testname-fn-timeout."

  563 |   }
  564 |
> 565 |   it('should allow to make many HMR updates', async () => {
      |   ^
  566 |     console.log('start')
  567 |     await new Promise((r) => setTimeout(r, 1000))
  568 |     const entrypointsSubscribtion = project.entrypointsSubscribe()

  at it (development/basic/next-rs-api.test.ts:565:3)
  at Object.describe (development/basic/next-rs-api.test.ts:121:1)

Read more about building and testing Next.js in contributing.md.