web: update to ESLint 9 (#10812)

* web: update to ESLint 9

ESLint 9 has been out for awhile now, and all of the plug-ins that we use have caught up, so it is
time to bite the bullet and upgrade.  This commit:

- upgrades to ESLint 9, and upgrades all associated plugins
- Replaces the `.eslintrc` and `.eslintignore` files with the new, "flat" configuration file,
  "eslint.config.mjs".
- Places the previous "precommit" and "nightmare" rules in `./scripts/eslint.precommit.mjs` and
  `./scripts/eslint.nightmare.mjs`, respectively
- Replaces the scripted wrappers for eslint (`eslint`, `eslint-precommit`) with a single executable
  that takes the arguments `--precommit`, which applies a stricter set of rules, and `--nightmare`,
  which applies an even more terrifyingly strict set of rules.
- Provides the scripted wrapper `./scripts/eslint.mjs` so that eslint can be run from `bun`, if one
  so chooses.
- Fixes *all* of the lint `eslint.config.mjs` now finds, including removing all of the `eslint`
  styling rules and overrides because Eslint now proudly leaves that entirely up to Prettier.

To shut Dependabot up about ESLint.

* Added explanation for no-console removal.

* web: did not need the old and unmaintained nightmare mode; it can be configured directly.

web/eslint.config.mjs

@@ -0,0 +1,80 @@
+import eslint from "@eslint/js";
+import tsparser from "@typescript-eslint/parser";
+import litconf from "eslint-plugin-lit";
+import wcconf from "eslint-plugin-wc";
+import globals from "globals";
+import tseslint from "typescript-eslint";
+
+export default [
+    // You would not believe how much this change has frustrated users: ["if an ignores key is used
+    // without any other keys in the configuration object, then the patterns act as global
+    // ignores"](https://eslint.org/docs/latest/use/configure/ignore)
+    {
+        ignores: [
+            "dist/",
+            // don't ever lint node_modules
+            "node_modules/",
+            ".storybook/*",
+            // don't lint build output (make sure it's set to your correct build folder name)
+            // don't lint nyc coverage output
+            "coverage/",
+            "src/locale-codes.ts",
+            "storybook-static/",
+            "src/locales/",
+        ],
+    },
+    eslint.configs.recommended,
+    wcconf.configs["flat/recommended"],
+    litconf.configs["flat/recommended"],
+    ...tseslint.configs.recommended,
+    {
+        languageOptions: {
+            parser: tsparser,
+            parserOptions: {
+                ecmaVersion: 12,
+                sourceType: "module",
+            },
+        },
+        files: ["src/**"],
+        rules: {
+            "no-unused-vars": "off",
+            "no-console": ["error", { allow: ["debug", "warn", "error"] }],
+            "@typescript-eslint/ban-ts-comment": "off",
+            "@typescript-eslint/no-unused-vars": [
+                "error",
+                {
+                    argsIgnorePattern: "^_",
+                    varsIgnorePattern: "^_",
+                    caughtErrorsIgnorePattern: "^_",
+                },
+            ],
+        },
+    },
+    {
+        languageOptions: {
+            parser: tsparser,
+            parserOptions: {
+                ecmaVersion: 12,
+                sourceType: "module",
+            },
+            globals: {
+                ...globals.nodeBuiltin,
+            },
+        },
+        files: ["scripts/*.mjs", "*.ts", "*.mjs"],
+        rules: {
+            "no-unused-vars": "off",
+            // We WANT our scripts to output to the console!
+            "no-console": "off",
+            "@typescript-eslint/ban-ts-comment": "off",
+            "@typescript-eslint/no-unused-vars": [
+                "error",
+                {
+                    argsIgnorePattern: "^_",
+                    varsIgnorePattern: "^_",
+                    caughtErrorsIgnorePattern: "^_",
+                },
+            ],
+        },
+    },
+];