3.x adjust localizeurl

[niels-numbers]

I made changes to align getLocalizedURL with the new approach of receiving locale via middleware. This allowed me to significantly simplify the logic and remove a lot of what seemed unnecessary. However, I may have gone a bit too far—feedback is welcome!

[niels-numbers]

Closing this. The package is now abandoned with niels-numbers/laravel-localizer set as the Composer replacement (#955), and the intent of this PR - route locale flowing through middleware rather than being passed explicitly to a URL helper - is the default in the successor: the SetLocale middleware registers the active locale via Laravel's URL::defaults(), so route('about') resolves to the locale-correct variant automatically without a manual override. No further work needed here.