misc: shortcut styled-jsx in external resolution (#56291)

This PR just shortcuts the styled-jsx resolution to tell webpack to
compile it immediately. I noticed this could cause an issue if
`config.experimental.bundlePagesExternals` was enabled.

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Author: feedthejim

Diff for: packages/next/src/build/handle-externals.ts

@@ -301,10 +301,8 @@ export function makeExternalHandler({
       return resolveResult.localRes
     }
 
-    // Forcedly resolve the styled-jsx installed by next.js,
-    // since `resolveExternal` cannot find the styled-jsx dep with pnpm
-    if (request === 'styled-jsx/style') {
-      resolveResult.res = defaultOverrides['styled-jsx/style']
+    if (request === 'styled-jsx/style' && !isAppLayer) {
+      return `commonjs ${defaultOverrides['styled-jsx/style']}`
     }
 
     const { res, isEsm } = resolveResult