feat: upgrade eslint to v9 in created projects

These changes include:
- Adding the new required dependencies for eslint v9
  (e.g. @eslint/eslintrc, @eslint/js, etc).
- Include eslint's compat package to continue using
  @react-native/eslint-config with the new config format.
- Move the inline eslint config (located in package.json) to the new
  flat file config format, in a separate file.

Author: Serchinastico

packages/create-react-native-library/templates/common/$package.json

@@ -77,19 +77,22 @@
   },
   "devDependencies": {
     "@commitlint/config-conventional": "^19.6.0",
+    "@eslint/compat": "^1.2.7",
+    "@eslint/eslintrc": "^3.3.0",
+    "@eslint/js": "^9.22.0",
     "@evilmartians/lefthook": "^1.5.0",
 <% if (example === 'vanilla' && (project.moduleConfig === 'turbo-modules' || project.viewConfig === 'fabric-view')) { -%>
     "@react-native-community/cli": "15.0.0-alpha.2",
 <% } -%>
-    "@react-native/eslint-config": "^0.73.1",
+    "@react-native/eslint-config": "^0.78.0",
     "@release-it/conventional-changelog": "^9.0.2",
     "@types/jest": "^29.5.5",
     "@types/react": "^18.2.44",
     "commitlint": "^19.6.1",
     "del-cli": "^5.1.0",
-    "eslint": "^8.51.0",
-    "eslint-config-prettier": "^9.0.0",
-    "eslint-plugin-prettier": "^5.0.1",
+    "eslint": "^9.22.0",
+    "eslint-config-prettier": "^10.1.1",
+    "eslint-plugin-prettier": "^5.2.3",
     "jest": "^29.7.0",
 <% if (project.moduleConfig === 'nitro-modules') { -%>
     "nitro-codegen": "^<%- versions.nitroCodegen %>",
@@ -156,30 +159,6 @@
       }
     }
   },
-  "eslintConfig": {
-    "root": true,
-    "extends": [
-      "@react-native",
-      "prettier"
-    ],
-    "rules": {
-      "react/react-in-jsx-scope": "off",
-      "prettier/prettier": [
-        "error",
-        {
-          "quoteProps": "consistent",
-          "singleQuote": true,
-          "tabWidth": 2,
-          "trailingComma": "es5",
-          "useTabs": false
-        }
-      ]
-    }
-  },
-  "eslintIgnore": [
-    "node_modules/",
-    "lib/"
-  ],
   "prettier": {
     "quoteProps": "consistent",
     "singleQuote": true,

packages/create-react-native-library/templates/common/eslint.config.mjs

@@ -0,0 +1,41 @@
+import { fixupConfigRules } from '@eslint/compat';
+import { FlatCompat } from '@eslint/eslintrc';
+import js from '@eslint/js';
+import prettier from 'eslint-plugin-prettier';
+import { defineConfig } from 'eslint/config';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+  recommendedConfig: js.configs.recommended,
+  allConfig: js.configs.all,
+});
+
+export default defineConfig([
+  {
+    extends: fixupConfigRules(compat.extends('@react-native', 'prettier')),
+    plugins: { prettier },
+    rules: {
+      'react/react-in-jsx-scope': 'off',
+      'prettier/prettier': [
+        'error',
+        {
+          quoteProps: 'consistent',
+          singleQuote: true,
+          tabWidth: 2,
+          trailingComma: 'es5',
+          useTabs: false,
+        },
+      ],
+    },
+  },
+  {
+    ignores: [
+      'node_modules/',
+      'lib/'
+    ],
+  },
+]);