Add copyright script (#7991)

Copied over our copyright script from the react repo. I made a small fix to handle shebangs.

package.json

@@ -21,7 +21,8 @@
     "postinstall": "is-ci || husky install .husky",
     "check-all": "npm-run-all prettier lint:fix tsc rss",
     "rss": "node scripts/generateRss.js",
-    "deadlinks": "node scripts/deadLinkChecker.js"
+    "deadlinks": "node scripts/deadLinkChecker.js",
+    "copyright": "node scripts/copyright.js"
   },
   "dependencies": {
     "@codesandbox/sandpack-react": "2.13.5",

scripts/copyright.js

@@ -0,0 +1,84 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+const fs = require('fs');
+const glob = require('glob');
+
+const META_COPYRIGHT_COMMENT_BLOCK =
+  `/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */`.trim() + '\n\n';
+
+const files = glob.sync('**/*.{js,ts,tsx,jsx,rs}', {
+  ignore: [
+    '**/dist/**',
+    '**/node_modules/**',
+    '**/tests/fixtures/**',
+    '**/__tests__/fixtures/**',
+  ],
+});
+
+const updatedFiles = new Map();
+let hasErrors = false;
+files.forEach((file) => {
+  try {
+    const result = processFile(file);
+    if (result != null) {
+      updatedFiles.set(file, result);
+    }
+  } catch (e) {
+    console.error(e);
+    hasErrors = true;
+  }
+});
+if (hasErrors) {
+  console.error('Update failed');
+  process.exit(1);
+} else {
+  for (const [file, source] of updatedFiles) {
+    fs.writeFileSync(file, source, 'utf8');
+  }
+  console.log('Update complete');
+}
+
+function processFile(file) {
+  if (fs.lstatSync(file).isDirectory()) {
+    return;
+  }
+  let source = fs.readFileSync(file, 'utf8');
+  let shebang = '';
+
+  if (source.startsWith('#!')) {
+    const newlineIndex = source.indexOf('\n');
+    if (newlineIndex === -1) {
+      shebang = `${source}\n`;
+      source = '';
+    } else {
+      shebang = source.slice(0, newlineIndex + 1);
+      source = source.slice(newlineIndex + 1);
+    }
+  }
+
+  if (source.indexOf(META_COPYRIGHT_COMMENT_BLOCK) === 0) {
+    return null;
+  }
+  if (/^\/\*\*/.test(source)) {
+    source = source.replace(/\/\*\*[^\/]+\/\s+/, META_COPYRIGHT_COMMENT_BLOCK);
+  } else {
+    source = `${META_COPYRIGHT_COMMENT_BLOCK}${source}`;
+  }
+
+  if (shebang) {
+    return `${shebang}${source}`;
+  }
+  return source;
+}