Refactor base server to get rid of the __server_context hack

[shuding]

This PR makes the Options type of base server configurable as well as assigning to this.serverOptions, so the web server can access it during constructor(). This gets rid of the dirty __server_context hack.

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

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js shu/c556	Change
buildDuration	19.1s	18.9s	-190ms
buildDurationCached	7.4s	7.4s	-61ms
nodeModulesSize	463 MB	463 MB	⚠️ +66 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	vercel/next.js shu/c556	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.871	3.963	⚠️ +0.09
/ avg req/sec	645.81	630.83	⚠️ -14.98
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.662	1.696	⚠️ +0.03
/error-in-render avg req/sec	1504.42	1474.29	⚠️ -30.13

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js shu/c556	Change
925.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42 kB	42 kB	✓
main-HASH.js gzip	28.6 kB	28.6 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	72.3 kB	72.3 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js shu/c556	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js shu/c556	Change
_app-HASH.js gzip	1.36 kB	1.36 kB	✓
_error-HASH.js gzip	193 B	193 B	✓
amp-HASH.js gzip	308 B	308 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	3.08 kB	3.08 kB	✓
head-HASH.js gzip	359 B	359 B	✓
hooks-HASH.js gzip	920 B	920 B	✓
image-HASH.js gzip	5.71 kB	5.71 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.64 kB	2.64 kB	✓
routerDirect..HASH.js gzip	320 B	320 B	✓
script-HASH.js gzip	391 B	391 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	16.3 kB	16.3 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js shu/c556	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js shu/c556	Change
index.html gzip	532 B	532 B	✓
link.html gzip	546 B	546 B	✓
withRouter.html gzip	528 B	528 B	✓
Overall change	1.61 kB	1.61 kB	✓

---

Default Build with SWC

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js shu/c556	Change
buildDuration	21.3s	21.2s	-88ms
buildDurationCached	7.5s	7.4s	-116ms
nodeModulesSize	463 MB	463 MB	⚠️ +66 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	vercel/next.js shu/c556	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.988	3.914	-0.07
/ avg req/sec	626.94	638.68	+11.74
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.682	1.694	⚠️ +0.01
/error-in-render avg req/sec	1486.6	1476.16	⚠️ -10.44

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js shu/c556	Change
925.HASH.js gzip	178 B	178 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	29.1 kB	29.1 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.9 kB	72.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js shu/c556	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js shu/c556	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	179 B	179 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	324 B	324 B	✓
dynamic-HASH.js gzip	3.08 kB	3.08 kB	✓
head-HASH.js gzip	357 B	357 B	✓
hooks-HASH.js gzip	921 B	921 B	✓
image-HASH.js gzip	5.76 kB	5.76 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	2.76 kB	2.76 kB	✓
routerDirect..HASH.js gzip	322 B	322 B	✓
script-HASH.js gzip	392 B	392 B	✓
withRouter-HASH.js gzip	317 B	317 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	16.5 kB	16.5 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js shu/c556	Change
_buildManifest.js gzip	458 B	458 B	✓
Overall change	458 B	458 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js shu/c556	Change
index.html gzip	530 B	530 B	✓
link.html gzip	543 B	543 B	✓
withRouter.html gzip	527 B	527 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: 69f7936