feat: Upgrade to ESLint 9

This commit upgrades us to the latest ESLint 9.  It adds better linting for TypeScript, in particular.  It removes eslint-plugin-airbnb and replaces it with the ‘recommended’ configs for eslint, typescript-eslint, react, and react-hooks.  It also adds the eslint stylistic config, and modifies it to match our existing code style.

Subsequent commits will fix all the styling issues found in this commit; the repository wasn’t linting very consistently before this, so somehow a bunch of stuff slipped through.

Author: davidjoy

.eslintignore

@@ -1,6 +1,5 @@
 __mocks__
-.eslintignore
-./.eslintrc.js
+./eslint.config.js
 .github
 .gitignore
 *.test.js

.eslintrc.js

@@ -0,0 +1,18 @@
+// @ts-check
+
+const tseslint = require('typescript-eslint');
+const eslintConfig = require('./tools/eslint/base.eslint.config.js');
+
+module.exports = tseslint.config(
+  {
+    extends: eslintConfig,
+  },
+  {
+    ignores: [
+      'tools/*',
+      'test-project/*',
+      'config/*',
+      'docs/*',
+    ],
+  },
+);