chore: move layer from chunking context to asset context

[ForsakenHarmony]

The asset context is a better place to store the layer, because it's affected by transitions unlike the chunking context

This PR also removes a bunch of unused code

Why?

See vercel/turborepo#6237 for the rationale
Also needs to wait for that PR to be merged

Closes NEXT-1814

Turbopack Changes

• chore: move layer from chunking context to asset context turborepo#6237

[ijjk]

Tests Passed

[ijjk]

Stats from current PR

Default Build

General

	vercel/next.js canary	vercel/next.js hrmny/web-1814-layer-on-assetcontext	Change
buildDuration	10.7s	10.8s	N/A
buildDurationCached	6.2s	6.3s	N/A
nodeModulesSize	174 MB	174 MB	N/A
nextStartRea..uration (ms)	504ms	499ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js hrmny/web-1814-layer-on-assetcontext	Change
199-HASH.js gzip	27.6 kB	27.6 kB	✓
3f784ff6-HASH.js gzip	53.3 kB	53.3 kB	✓
99.HASH.js gzip	182 B	182 B	✓
framework-HASH.js gzip	45.3 kB	45.3 kB	✓
main-app-HASH.js gzip	254 B	252 B	N/A
main-HASH.js gzip	32.9 kB	32.9 kB	N/A
webpack-HASH.js gzip	1.75 kB	1.75 kB	N/A
Overall change	126 kB	126 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js hrmny/web-1814-layer-on-assetcontext	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js hrmny/web-1814-layer-on-assetcontext	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	2.57 kB	2.57 kB	N/A
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	4.36 kB	4.36 kB	N/A
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.64 kB	2.63 kB	N/A
routerDirect..HASH.js gzip	312 B	311 B	N/A
script-HASH.js gzip	385 B	384 B	N/A
withRouter-HASH.js gzip	307 B	308 B	N/A
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	1.08 kB	1.08 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js hrmny/web-1814-layer-on-assetcontext	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 hrmny/web-1814-layer-on-assetcontext	Change
index.html gzip	527 B	529 B	N/A
link.html gzip	542 B	541 B	N/A
withRouter.html gzip	525 B	525 B	✓
Overall change	525 B	525 B	✓

Edge SSR bundle Size

	vercel/next.js canary	vercel/next.js hrmny/web-1814-layer-on-assetcontext	Change
edge-ssr.js gzip	93.9 kB	93.9 kB	N/A
page.js gzip	155 kB	155 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	vercel/next.js hrmny/web-1814-layer-on-assetcontext	Change
middleware-b..fest.js gzip	623 B	626 B	N/A
middleware-r..fest.js gzip	150 B	151 B	N/A
middleware.js gzip	22.9 kB	22.9 kB	N/A
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	1.92 kB	1.92 kB	✓

Diff details

Diff for page.js

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Diff for edge-ssr.js

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Commit: c0b064a