Allow specifying namespace when generating routes.

[lonnieezell]

Description
If you need to override all of the auth controllers it is a pain to have to specify all of the routes manually when all you need is to change the namespace. This change allows you to pass a namespace option along into the auth()->routes() call.

auth()->routes($routes, ['namespace' => 'App\Controllers\Auth']);

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide