Inherit title and description from metadata into social cards

[huozhi]

Social metadata will be display properly if there's title and description configured.
If you have title and description configured in metadata, some people's intuition will be "yes I had them, they should be the same if I have openGraph or twitter".

This PR improves the configuration that you don't have to configure them as duplicate both in top metadata export and metadata.openGraph or metadata.twitter. But we don't always assign them if you don't configure social cards (open graph or twitter), this way users should be able to omit social cards if possible.

x-ref: feedback from slack

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js inherit-metadata-title-and-desc	Change
buildDuration	10.5s	10.7s	⚠️ +238ms
buildDurationCached	5.9s	6s	N/A
nodeModulesSize	175 MB	175 MB	⚠️ +22.4 kB
nextStartRea..uration (ms)	416ms	418ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js inherit-metadata-title-and-desc	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 inherit-metadata-title-and-desc	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js inherit-metadata-title-and-desc	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 inherit-metadata-title-and-desc	Change
_buildManifest.js gzip	484 B	484 B	✓
Overall change	484 B	484 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js inherit-metadata-title-and-desc	Change
index.html gzip	528 B	527 B	N/A
link.html gzip	542 B	544 B	N/A
withRouter.html gzip	525 B	522 B	N/A
Overall change	0 B	0 B	✓

Edge SSR bundle Size Overall increase ⚠️

	vercel/next.js canary	vercel/next.js inherit-metadata-title-and-desc	Change
edge-ssr.js gzip	96.1 kB	96.1 kB	N/A
page.js gzip	140 kB	140 kB	⚠️ +104 B
Overall change	140 kB	140 kB	⚠️ +104 B

Middleware size

	vercel/next.js canary	vercel/next.js inherit-metadata-title-and-desc	Change
middleware-b..fest.js gzip	626 B	625 B	N/A
middleware-r..fest.js gzip	148 B	151 B	N/A
middleware.js gzip	24.8 kB	24.8 kB	✓
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	26.8 kB	26.8 kB	✓

Diff details

Diff for page.js

Diff too large to display

Commit: 30c7978

[ijjk]

Tests Passed