feat(v2): official CodeSandbox support (#3717)

* feat:added support for codesandbox

* added sandbox config file

* feat:added script to generate template for codesandbox

* added examples:generate script to package.json file

* added failing path to eslintignore

* added script to eslintignore

* added cleaning feature to script

* deleted sandbox script in root

* changed comment in codesandboxscript file

* update codesandboxscript.js + revert bad package.json changes

* eslint should check codesandboxscript

Co-authored-by: slorber <lorber.sebastien@gmail.com>

examples/facebook/.eslintrc.js

@@ -0,0 +1,60 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+const OFF = 0;
+const WARNING = 1;
+const ERROR = 2;
+
+module.exports = {
+  root: true,
+  env: {
+    browser: true,
+    commonjs: true,
+    jest: true,
+    node: true,
+  },
+  parser: 'babel-eslint',
+  parserOptions: {
+    allowImportExportEverywhere: true,
+  },
+  extends: ['airbnb', 'prettier', 'prettier/react'],
+  plugins: ['react-hooks', 'header'],
+  rules: {
+    // Ignore certain webpack alias because it can't be resolved
+    'import/no-unresolved': [
+      ERROR,
+      {ignore: ['^@theme', '^@docusaurus', '^@generated']},
+    ],
+    'import/extensions': OFF,
+    'header/header': [
+      ERROR,
+      'block',
+
+      [
+        '*',
+        ' * Copyright (c) Facebook, Inc. and its affiliates.',
+        ' *',
+        ' * This source code is licensed under the MIT license found in the',
+        ' * LICENSE file in the root directory of this source tree.',
+        ' *',
+        // Unfortunately eslint-plugin-header doesn't support optional lines.
+        // If you want to enforce your website JS files to have @flow or @format,
+        // modify these lines accordingly.
+        {
+          pattern: '.* @format',
+        },
+        ' ',
+      ],
+    ],
+    'react/jsx-closing-bracket-location': OFF, // Conflicts with Prettier.
+    'react/jsx-filename-extension': OFF,
+    'react-hooks/rules-of-hooks': ERROR,
+    'react/prop-types': OFF, // PropTypes aren't used much these days.
+  },
+};