Make module types explicit and convert some to ESM (#15964)

build-scripts/util.cjs

@@ -0,0 +1,16 @@
+const path = require("path");
+const fs = require("fs");
+
+// Helper function to map recursively over files in a folder and it's subfolders
+module.exports.mapFiles = function mapFiles(startPath, filter, mapFunc) {
+  const files = fs.readdirSync(startPath);
+  for (let i = 0; i < files.length; i++) {
+    const filename = path.join(startPath, files[i]);
+    const stat = fs.lstatSync(filename);
+    if (stat.isDirectory()) {
+      mapFiles(filename, filter, mapFunc);
+    } else if (filename.indexOf(filter) >= 0) {
+      mapFunc(filename);
+    }
+  }
+};