feat: update eslint to v9

BREAKING CHANGE: `@adfinis/eslint-config` now required the usage of
ESLint v9.

README.md

@@ -6,7 +6,7 @@ This package contains our internally used eslint config.
 
 To install this package, simply run
 
-```bash
+```console
 pnpm add -D @adfinis/eslint-config \
             eslint \
             eslint-config-prettier \
@@ -17,17 +17,22 @@ pnpm add -D @adfinis/eslint-config \
 Then add the following to your `.eslintrc.js`
 
 ```js
-module.exports = {
-  extends: "@adfinis/eslint-config",
-};
+import adfinisConfig from "@adfinis/eslint-config";
+
+export default [
+  ...adfinisConfig,
+  {
+    // Custom rules for your project
+  },
+];
 ```
 
 ### Ember
 
 If you are using it in an ember app or addon you can use the config for
 ember:
 
-```bash
+```console
 pnpm add -D @adfinis/eslint-config \
             @babel/eslint-parser \
             @babel/plugin-proposal-decorators \
@@ -44,26 +49,25 @@ pnpm add -D @adfinis/eslint-config \
 For an app replace your `.eslintrc.js` with this:
 
 ```js
-module.exports = {
-  extends: "@adfinis/eslint-config/ember-app",
-};
+import adfinisEmberAppConfig from "@adfinis/eslint-config/ember-app";
+
+export default [
+  ...adfinisEmberAppConfig,
+  {
+    // Custom rules for your project
+  },
+];
 ```
 
 Or for an addon replace your `.eslintrc.js` with this:
 
 ```js
-module.exports = {
-  extends: "@adfinis/eslint-config/ember-addon",
-};
+import adfinisEmberAddonConfig from "@adfinis/eslint-config/ember-addon";
+
+export default [
+  ...adfinisEmberAddonConfig,
+  {
+    // Custom rules for your project
+  },
+];
 ```
-
-## Maintaining
-
-Since we want to keep the config in sync with Ember.js' config, we need to
-synchronize it from time to time. This can be done very easily by running
-`pnpm update-blueprints` and verifying the changes.
-
-There is also a [Github Action](https://github.com/adfinis/eslint-config/actions/workflows/update-blueprints.yml)
-that runs this script automatically every week at Friday 12:00 and opens a
-[PR](https://github.com/adfinis/eslint-config/pulls?q=is%3Aopen+is%3Apr+label%3Aupdate-blueprints)
-if there is a change.

ember-addon.mjs

@@ -0,0 +1,122 @@
+/**
+ * Debugging:
+ *   https://eslint.org/docs/latest/use/configure/debug
+ *  ----------------------------------------------------
+ *
+ *   Print a file's calculated configuration
+ *
+ *     npx eslint --print-config path/to/file.js
+ *
+ *   Inspecting the config
+ *
+ *     npx eslint --inspect-config
+ *
+ */
+import babelParser from "@babel/eslint-parser";
+import js from "@eslint/js";
+import ember from "eslint-plugin-ember/recommended";
+import n from "eslint-plugin-n";
+import prettier from "eslint-plugin-prettier/recommended";
+import qunit from "eslint-plugin-qunit";
+import globals from "globals";
+
+import adfinis from "./index.mjs";
+
+const esmParserOptions = {
+  ecmaFeatures: { modules: true },
+  ecmaVersion: "latest",
+  requireConfigFile: false,
+  babelOptions: {
+    plugins: [
+      ["@babel/plugin-proposal-decorators", { decoratorsBeforeExport: true }],
+    ],
+  },
+};
+
+export default [
+  js.configs.recommended,
+  prettier,
+  ember.configs.base,
+  ember.configs.gjs,
+  ...adfinis,
+  /**
+   * Ignores must be in their own object
+   * https://eslint.org/docs/latest/use/configure/ignore
+   */
+  {
+    ignores: ["dist/", "node_modules/", "coverage/", "!**/.*"],
+  },
+  /**
+   * https://eslint.org/docs/latest/use/configure/configuration-files#configuring-linter-options
+   */
+  {
+    linterOptions: {
+      reportUnusedDisableDirectives: "error",
+    },
+  },
+  {
+    files: ["**/*.js"],
+    languageOptions: {
+      parser: babelParser,
+    },
+  },
+  {
+    files: ["**/*.{js,gjs}"],
+    languageOptions: {
+      parserOptions: esmParserOptions,
+      globals: {
+        ...globals.browser,
+      },
+    },
+  },
+  {
+    files: ["tests/**/*-test.{js,gjs}"],
+    plugins: {
+      qunit,
+    },
+  },
+  /**
+   * CJS node files
+   */
+  {
+    files: [
+      "**/*.cjs",
+      "config/**/*.js",
+      "testem.js",
+      "testem*.js",
+      ".prettierrc.js",
+      ".stylelintrc.js",
+      ".template-lintrc.js",
+      "ember-cli-build.js",
+    ],
+    plugins: {
+      n,
+    },
+
+    languageOptions: {
+      sourceType: "script",
+      ecmaVersion: "latest",
+      globals: {
+        ...globals.node,
+      },
+    },
+  },
+  /**
+   * ESM node files
+   */
+  {
+    files: ["**/*.mjs"],
+    plugins: {
+      n,
+    },
+
+    languageOptions: {
+      sourceType: "module",
+      ecmaVersion: "latest",
+      parserOptions: esmParserOptions,
+      globals: {
+        ...globals.node,
+      },
+    },
+  },
+];