Fix next/server apit push alias for ESM pkg (#61721)

We have a modularize imports config for `next/server` before, which will
transform the `next/server` imports to directly import from the actual
file, for instance: `import { NextRequest } from 'next/server'` will
become `import { NextRequest } from
'next/dist/server/web/exports/next-request'`, where the NextRequest is
exported as default export. This is fine in most case until you're using
a ESM pkg, then it will be resolved as `{ default: NextRequest }`
according to the spec. Since it's a ESM import to a CJS module in
`next/dist`.

Since we already have the ESM alias introduced in #59852 , this can
handle the case more properly.

Remove the modularize imports config for `next/server`, use the ESM api
alias instead.

Migrate the cjs optimizer tests from middleware to a separate endpoint
`/cjs/server`. As now ESM imports for next/server are not going to get
tree-shaken in dev, but since we don't have image response there it's
still fine.

Closes NEXT-2376
Closes NEXT-2374

Author: huozhi

packages/next/server.js

@@ -9,11 +9,8 @@ const serverExports = {
     .userAgentFromString,
   userAgent: require('next/dist/server/web/spec-extension/user-agent')
     .userAgent,
-}
-
-if (typeof URLPattern !== 'undefined') {
-  // eslint-disable-next-line no-undef
-  serverExports.URLPattern = URLPattern
+  URLPattern: require('next/dist/server/web/spec-extension/url-pattern')
+    .URLPattern,
 }
 
 // https://nodejs.org/api/esm.html#commonjs-namespaces

packages/next/src/build/create-compiler-aliases.ts

@@ -205,6 +205,7 @@ export function createNextApiEsmAliases() {
     navigation: 'next/dist/api/navigation',
     headers: 'next/dist/api/headers',
     og: 'next/dist/api/og',
+    server: 'next/dist/api/server',
     // pages api
     document: 'next/dist/api/document',
     app: 'next/dist/api/app',

packages/next/src/server/config.ts

@@ -831,9 +831,6 @@ function assignDefaults(
     lodash: {
       transform: 'lodash/{{member}}',
     },
-    'next/server': {
-      transform: 'next/dist/server/web/exports/{{ kebabCase member }}',
-    },
   }
 
   const userProvidedOptimizePackageImports =

packages/next/src/server/web/exports/image-response.ts

@@ -1,8 +1,7 @@
 // Alias index file of next/server for edge runtime for tree-shaking purpose
 
-export { default as ImageResponse } from './image-response'
-export { default as NextRequest } from './next-request'
-export { default as NextResponse } from './next-response'
-export { default as userAgent } from './user-agent'
-export { default as userAgentFromString } from './user-agent-from-string'
-export { default as URLPattern } from './url-pattern'
+export { ImageResponse } from '../spec-extension/image-response'
+export { NextRequest } from '../spec-extension/request'
+export { NextResponse } from '../spec-extension/response'
+export { userAgent, userAgentFromString } from '../spec-extension/user-agent'
+export { URLPattern } from '../spec-extension/url-pattern'