Upgrade ESLint to v9 with flat config (#9680)

* Upgrade ESLint to v9 with flat config

- Upgrade eslint from v8 to v9.18.0
- Migrate from .eslintrc.js to eslint.config.mjs (flat config)
- Upgrade typescript-eslint to v8.20.0 (unified package)
- Replace eslint-plugin-import with eslint-plugin-import-x for flat config support
- Add globals package for environment globals
- Update eslint-plugin-bsky-internal with proper meta objects for ESLint v9
- Fix deprecated context.getScope() API usage
- Update bskyembed to use flat config
- Remove deprecated --ext flag from lint scripts
- Configure rules to maintain previous behavior while using new ESLint version

* Fix varsIgnorePattern to require character after underscore

Restore the original pattern `^_.+` instead of `^_` so that lingui's
`const { _ } = useLingui()` will still be flagged when unused.

* Update ESLint rule tests for flat config format

- Update RuleTester to use flat config languageOptions instead of
  eslintrc parser format
- Remove duplicate test case that ESLint v9 now detects
- Add Jest globals for test files

* update eslint package versions

* lint android a11y

* enable typechecked rules, switch them to warn

* fix yarn lock ci

* Fix CI failure

* Remove unused globals?

* Organize a bit, add quiet to main lint command

* Allow ternary

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Eric Bailey <git@esb.lol>

eslint/__tests__/avoid-unwrapped-text.test.js

@@ -1,14 +1,17 @@
 const {RuleTester} = require('eslint')
+const tseslint = require('typescript-eslint')
 const avoidUnwrappedText = require('../avoid-unwrapped-text')
 
 const ruleTester = new RuleTester({
-  parser: require.resolve('@typescript-eslint/parser'),
-  parserOptions: {
-    ecmaFeatures: {
-      jsx: true,
+  languageOptions: {
+    parser: tseslint.parser,
+    parserOptions: {
+      ecmaFeatures: {
+        jsx: true,
+      },
+      ecmaVersion: 'latest',
+      sourceType: 'module',
     },
-    ecmaVersion: 6,
-    sourceType: 'module',
   },
 })
 
@@ -773,15 +776,6 @@ function MyText({ foo }) {
         errors: 1,
       },
 
-      {
-        code: `
-<View>
-  <Trans>{'foo'}</Trans>
-</View>
-       `,
-        errors: 1,
-      },
-
       {
         code: `
 <View prop={