Update to use eslint9 (#7876)

* Update to use eslint9

Updates the package to use eslint9. This switches to a flat config file and also updates a few dependencies

I generally tried to keep the existing logic and rules with this change. We can revisit these later

I did end up having to make a few code changes for new errors that showed up after updating

* Update all pipelines to node 20

The release pipelines should already be using this but the pr pipeline was on an old version

* Update common-setup instead

* Add back missing rules

* Fix webviews rule

* Remove some bad eslint comments

---------

Co-authored-by: Alex Ross <38270282+alexr00@users.noreply.github.com>

Author: mjbvz

.eslintignore

@@ -31,6 +31,8 @@ extends:
 
     l10nSourcePaths: ./src
 
+    nodeVersion: "20.x"
+
     buildSteps:
       - script: yarn install --frozen-lockfile --check-files
         displayName: Install dependencies

.eslintrc.base.json

@@ -28,6 +28,8 @@ extends:
 
     l10nSourcePaths: ./src
 
+    nodeVersion: "20.x"
+
     buildSteps:
       - script: yarn install --frozen-lockfile --check-files
         displayName: Install dependencies

.eslintrc.browser.json

@@ -5,7 +5,7 @@
 
 'use strict';
 
-module.exports = {
+exports.rules = {
 	'public-methods-well-defined-types': require('./public-methods-well-defined-types'),
 	'no-any-except-union-method-signature': require('./no-any-except-union-method-signature'),
 	'no-pr-in-user-strings': require('./no-pr-in-user-strings'),

.eslintrc.js

@@ -59,9 +59,11 @@ module.exports = {
 
 				// Type references with inline type arguments: Promise<{x: string}>, Array<{y: number}>
 				case 'TSTypeReference':
-					// Check if any type arguments contain inline types
-					if (typeNode.typeParameters && typeNode.typeParameters.params) {
-						return typeNode.typeParameters.params.some(isInlineType);
+					// ESLint 9 / @typescript-eslint v8 may expose generic instantiations on `typeArguments` instead of `typeParameters`.
+					// Support both shapes defensively.
+					const typeArgs = typeNode.typeParameters || typeNode.typeArguments;
+					if (typeArgs && typeArgs.params) {
+						return typeArgs.params.some(isInlineType);
 					}
 					return false;