Refactor the middleware SSR loader

[shuding]

Initial step for #31506, to move the adapter logic out of the loader output string so it will be easier to reuse code in the future. Also, more options are passed to the loader to align with the serverless loader.

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 by running yarn lint

[huozhi]

Nice work! Could you update error handling changes from #31466?

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	shuding/next.js shu/5fa8	Change
buildDuration	18.7s	18.8s	⚠️ +77ms
buildDurationCached	3.7s	3.8s	⚠️ +70ms
nodeModulesSize	336 MB	336 MB	⚠️ +4.79 kB

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	shuding/next.js shu/5fa8	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.043	3.038	-0.01
/ avg req/sec	821.43	822.8	+1.37
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.394	1.423	⚠️ +0.03
/error-in-render avg req/sec	1793	1757.04	⚠️ -35.96

Client Bundles (main, webpack, commons)

	vercel/next.js canary	shuding/next.js shu/5fa8	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	shuding/next.js shu/5fa8	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	shuding/next.js shu/5fa8	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	shuding/next.js shu/5fa8	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	shuding/next.js shu/5fa8	Change
index.html gzip	523 B	523 B	✓
link.html gzip	536 B	536 B	✓
withRouter.html gzip	517 B	517 B	✓
Overall change	1.58 kB	1.58 kB	✓

---

Default Build with SWC (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	shuding/next.js shu/5fa8	Change
buildDuration	20s	20s	⚠️ +48ms
buildDurationCached	3.7s	3.7s	⚠️ +17ms
nodeModulesSize	336 MB	336 MB	⚠️ +4.79 kB

Page Load Tests Overall increase ✓

	vercel/next.js canary	shuding/next.js shu/5fa8	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.004	3.005	0
/ avg req/sec	832.19	831.9	⚠️ -0.29
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.397	1.381	-0.02
/error-in-render avg req/sec	1789.93	1810.88	+20.95

Client Bundles (main, webpack, commons)

	vercel/next.js canary	shuding/next.js shu/5fa8	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	shuding/next.js shu/5fa8	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	shuding/next.js shu/5fa8	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	shuding/next.js shu/5fa8	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	shuding/next.js shu/5fa8	Change
index.html gzip	524 B	524 B	✓
link.html gzip	535 B	535 B	✓
withRouter.html gzip	517 B	517 B	✓
Overall change	1.58 kB	1.58 kB	✓

Commit: fc7af49