[.next/trace] Add tags for webpack build worker

[mknichel]

This PR adds a tag to the next-build span to identify whether the build is using the webpack build workers and/or has a custom webpack config which can be used during debugging traces.

[ijjk]

Allow CI Workflow Run

• approve CI run for commit: a68faf0

Note: this should only be enabled once the PR is ready to go and can only be enabled by a maintainer

[ijjk]

Stats from current PR

Default Build

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js mknichel/add-tags-to-next-build-span	Change
buildDuration	10.5s	10.6s	N/A
buildDurationCached	6.1s	6.2s	N/A
nodeModulesSize	175 MB	175 MB	⚠️ +1.19 kB
nextStartRea..uration (ms)	402ms	420ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js mknichel/add-tags-to-next-build-span	Change
199-HASH.js gzip	30 kB	30 kB	N/A
3f784ff6-HASH.js gzip	53.2 kB	53.2 kB	✓
494.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	33.1 kB	33.1 kB	N/A
webpack-HASH.js gzip	1.75 kB	1.75 kB	N/A
Overall change	98.9 kB	98.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js mknichel/add-tags-to-next-build-span	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js mknichel/add-tags-to-next-build-span	Change
_app-HASH.js gzip	205 B	205 B	✓
_error-HASH.js gzip	182 B	181 B	N/A
amp-HASH.js gzip	505 B	507 B	N/A
css-HASH.js gzip	322 B	323 B	N/A
dynamic-HASH.js gzip	2.59 kB	2.59 kB	N/A
edge-ssr-HASH.js gzip	258 B	259 B	N/A
head-HASH.js gzip	348 B	347 B	N/A
hooks-HASH.js gzip	369 B	368 B	N/A
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	318 B	318 B	✓
script-HASH.js gzip	384 B	383 B	N/A
withRouter-HASH.js gzip	319 B	320 B	N/A
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	885 B	885 B	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js mknichel/add-tags-to-next-build-span	Change
_buildManifest.js gzip	484 B	484 B	✓
Overall change	484 B	484 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js mknichel/add-tags-to-next-build-span	Change
index.html gzip	527 B	529 B	N/A
link.html gzip	540 B	543 B	N/A
withRouter.html gzip	523 B	523 B	✓
Overall change	523 B	523 B	✓

Edge SSR bundle Size

	vercel/next.js canary	vercel/next.js mknichel/add-tags-to-next-build-span	Change
edge-ssr.js gzip	96.1 kB	96.1 kB	N/A
page.js gzip	140 kB	140 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	vercel/next.js mknichel/add-tags-to-next-build-span	Change
middleware-b..fest.js gzip	624 B	626 B	N/A
middleware-r..fest.js gzip	148 B	151 B	N/A
middleware.js gzip	23 kB	23 kB	✓
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	25 kB	25 kB	✓

Commit: a68faf0