feat: convert to native ESM module (#1038)

BREAKING CHANGE: _lint-staged_ is now a pure ESM module, and thus
requires Node.js version `^12.20.0 || ^14.13.1 || >=16.0.0`.

To update your Node.js integration, please use:

```js
// const lintStaged = require('lint-staged')
import lintStaged from 'lint-staged'
```

Author: iiroj

.babelrc

@@ -6,19 +6,35 @@
       "experimentalObjectRestSpread": true
     },
     "requireConfigFile": false,
-    "sourceType": "script"
+    "sourceType": "module"
   },
   "env": {
     "es6": true,
     "node": true
   },
-  "extends": ["eslint:recommended", "prettier"],
+  "extends": ["eslint:recommended", "plugin:import/recommended", "prettier"],
   "plugins": ["node", "import", "prettier"],
   "rules": {
+    "import/order": [
+      "error",
+      {
+        "groups": [
+          "builtin",
+          "external",
+          "internal",
+          "parent",
+          "sibling",
+          "index",
+          "object",
+          "type"
+        ],
+        "newlines-between": "always"
+      }
+    ],
     "no-console": "off",
-    "node/no-unsupported-features/node-builtins": "off",
-    "node/no-unsupported-features/es-syntax": ["error", { "version": ">=10.13.0" }],
-    "node/no-unsupported-features/es-builtins": ["error", { "version": ">=10.13.0" }],
+    "node/no-unsupported-features/es-builtins": "error",
+    "node/no-unsupported-features/es-syntax": ["error", { "ignores": ["modules"] }],
+    "node/no-unsupported-features/node-builtins": "error",
     "prettier/prettier": "error"
   }
 }