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

Author: mjbvz

.eslintignore

@@ -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'),