perf: use fs.readdirSync with withFileTypes (#52340)

There is no need to make a `fs.statSync` call for each file while reading a directory, since `fs.readdirSync` supports `withFileTypes` property that returns a `fs.Dirent` which includes the necessary information for detecting if the particular item is directory or not.

packages/next/src/server/lib/recursive-readdir-sync.ts

@@ -13,13 +13,12 @@ export function recursiveReadDirSync(
   /** Used to replace the initial path, only the relative path is left, it's faster than path.relative. */
   rootDir = dir
 ): string[] {
-  const result = fs.readdirSync(dir)
+  const result = fs.readdirSync(dir, { withFileTypes: true })
 
-  result.forEach((part: string) => {
-    const absolutePath = join(dir, part)
-    const pathStat = fs.statSync(absolutePath)
+  result.forEach((part) => {
+    const absolutePath = join(dir, part.name)
 
-    if (pathStat.isDirectory()) {
+    if (part.isDirectory()) {
       recursiveReadDirSync(absolutePath, arr, rootDir)
       return
     }