add filename to babel warning about anonymous function default exports

[bywo]

fixes #29667

I didn't add an integration test, but I can take a stab at it if you point me in the right direction!

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
buildDuration	21.7s	21.4s	-304ms
buildDurationCached	4.3s	4.2s	-81ms
nodeModulesSize	335 MB	335 MB	⚠️ +297 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.739	3.818	⚠️ +0.08
/ avg req/sec	668.67	654.88	⚠️ -13.79
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.956	2.049	⚠️ +0.09
/error-in-render avg req/sec	1277.96	1220.37	⚠️ -57.59

Client Bundles (main, webpack, commons)

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	28.3 kB	28.3 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.2 kB	72.2 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
_app-HASH.js gzip	1.37 kB	1.37 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	635 B	635 B	✓
image-HASH.js gzip	4.44 kB	4.44 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	1.87 kB	1.87 kB	✓
routerDirect..HASH.js gzip	321 B	321 B	✓
script-HASH.js gzip	383 B	383 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.3 kB	13.3 kB	✓

Client Build Manifests

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
index.html gzip	521 B	521 B	✓
link.html gzip	534 B	534 B	✓
withRouter.html gzip	515 B	515 B	✓
Overall change	1.57 kB	1.57 kB	✓

---

Default Build with SWC (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
buildDuration	23.4s	23s	-371ms
buildDurationCached	4.4s	4.2s	-140ms
nodeModulesSize	335 MB	335 MB	⚠️ +297 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.891	3.737	-0.15
/ avg req/sec	642.53	669.06	+26.53
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.023	2.054	⚠️ +0.03
/error-in-render avg req/sec	1235.7	1216.92	⚠️ -18.78

Client Bundles (main, webpack, commons)

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.5 kB	28.5 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	72.5 kB	72.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	305 B	305 B	✓
css-HASH.js gzip	321 B	321 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	622 B	622 B	✓
image-HASH.js gzip	4.46 kB	4.46 kB	✓
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	1.91 kB	1.91 kB	✓
routerDirect..HASH.js gzip	314 B	314 B	✓
script-HASH.js gzip	375 B	375 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.2 kB	13.2 kB	✓

Client Build Manifests

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	bywo/next.js anonymous-export-filename	Change
index.html gzip	523 B	523 B	✓
link.html gzip	535 B	535 B	✓
withRouter.html gzip	516 B	516 B	✓
Overall change	1.57 kB	1.57 kB	✓

Commit: b314ee7