vfs: remove internalModuleStat from provider base class

Move the internalModuleStat logic into VirtualFileSystem where it is
used internally, instead of exposing it on the VFSProvider base class.
The method now uses statSync directly rather than delegating to the
provider.

Author: mcollina

lib/internal/vfs/file_system.js

@@ -609,8 +609,11 @@ class VirtualFileSystem {
    */
   internalModuleStat(filePath) {
     try {
-      const providerPath = this.#toProviderPath(filePath);
-      return this[kProvider].internalModuleStat(providerPath);
+      const stats = this.statSync(filePath);
+      if (stats.isDirectory()) {
+        return 1;
+      }
+      return 0;
     } catch {
       return -2;
     }

lib/internal/vfs/provider.js

@@ -387,24 +387,6 @@ class VirtualProvider {
     this.writeFileSync(dest, content);
   }
 
-  /**
-   * Returns the stat result code for module resolution.
-   * Used by Module._stat override.
-   * @param {string} path The path to check
-   * @returns {number} 0 for file, 1 for directory, -2 for not found
-   */
-  internalModuleStat(path) {
-    try {
-      const stats = this.statSync(path);
-      if (stats.isDirectory()) {
-        return 1;
-      }
-      return 0;
-    } catch {
-      return -2; // ENOENT
-    }
-  }
-
   /**
    * Gets the real path by resolving symlinks.
    * @param {string} path The path