Add type annotation for NextConfig to CNA typescript template

[stefanprobst]

This adds a type annotation for the NextConfig type to next.config.js in the create-next-app typescript template.

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
buildDuration	15.4s	15.1s	-301ms
buildDurationCached	3.5s	3.3s	-226ms
nodeModulesSize	50.2 MB	50.2 MB	✓

Page Load Tests Overall increase ✓

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.729	2.729	✓
/ avg req/sec	916.15	916.09	⚠️ -0.06
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.647	1.541	-0.11
/error-in-render avg req/sec	1518	1621.89	+103.89

Client Bundles (main, webpack, commons)

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
745.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	23.1 kB	23.1 kB	✓
webpack-HASH.js gzip	1.5 kB	1.5 kB	✓
Overall change	67 kB	67 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
polyfills-HASH.js gzip	31.1 kB	31.1 kB	✓
Overall change	31.1 kB	31.1 kB	✓

Client Pages

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
_app-HASH.js gzip	980 B	980 B	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	329 B	329 B	✓
dynamic-HASH.js gzip	2.52 kB	2.52 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	904 B	904 B	✓
image-HASH.js gzip	4.12 kB	4.12 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	1.66 kB	1.66 kB	✓
routerDirect..HASH.js gzip	319 B	319 B	✓
script-HASH.js gzip	387 B	387 B	✓
withRouter-HASH.js gzip	320 B	320 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	12.8 kB	12.8 kB	✓

Client Build Manifests

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
_buildManifest.js gzip	490 B	490 B	✓
Overall change	490 B	490 B	✓

Rendered Page Sizes

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
index.html gzip	531 B	531 B	✓
link.html gzip	543 B	543 B	✓
withRouter.html gzip	524 B	524 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Webpack 4 Mode (Increase detected ⚠️)

General

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
buildDuration	12.5s	12.8s	⚠️ +253ms
buildDurationCached	5.1s	4.9s	-154ms
nodeModulesSize	50.2 MB	50.2 MB	✓

Page Load Tests Overall increase ✓

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.72	2.643	-0.08
/ avg req/sec	919.02	945.89	+26.87
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.554	1.477	-0.08
/error-in-render avg req/sec	1608.47	1692.8	+84.33

Client Bundles (main, webpack, commons)

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
17.HASH.js gzip	185 B	185 B	✓
677f882d2ed8..HASH.js gzip	14 kB	14 kB	✓
framework.HASH.js gzip	41.9 kB	41.9 kB	✓
main-HASH.js gzip	10.6 kB	10.6 kB	✓
webpack-HASH.js gzip	1.19 kB	1.19 kB	✓
Overall change	67.8 kB	67.8 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
polyfills-HASH.js gzip	31.3 kB	31.3 kB	✓
Overall change	31.3 kB	31.3 kB	✓

Client Pages

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
_app-HASH.js gzip	965 B	965 B	✓
_error-HASH.js gzip	3.71 kB	3.71 kB	✓
amp-HASH.js gzip	552 B	552 B	✓
css-HASH.js gzip	333 B	333 B	✓
dynamic-HASH.js gzip	2.71 kB	2.71 kB	✓
head-HASH.js gzip	2.97 kB	2.97 kB	✓
hooks-HASH.js gzip	911 B	911 B	✓
index-HASH.js gzip	231 B	231 B	✓
link-HASH.js gzip	1.64 kB	1.64 kB	✓
routerDirect..HASH.js gzip	298 B	298 B	✓
script-HASH.js gzip	2.94 kB	2.94 kB	✓
withRouter-HASH.js gzip	294 B	294 B	✓
e025d2764813..52f.css gzip	125 B	125 B	✓
Overall change	17.7 kB	17.7 kB	✓

Client Build Manifests

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
_buildManifest.js gzip	498 B	498 B	✓
Overall change	498 B	498 B	✓

Rendered Page Sizes

	vercel/next.js canary	stefanprobst/next.js add-config-type-to-cna	Change
index.html gzip	577 B	577 B	✓
link.html gzip	589 B	589 B	✓
withRouter.html gzip	571 B	571 B	✓
Overall change	1.74 kB	1.74 kB	✓

Commit: 2566265