Move to modern directory structure, extend AbstractBundle

[tacman]

AbstractBundle simplifies the setup a lot, available with Symfony 6.1+

https://symfony.com/blog/new-in-symfony-6-1-simpler-bundle-extension-and-configuration

Also, things like templates and config have moved:

https://symfony.com/doc/current/bundles/best_practices.html

I always disliked looking in Resources/views for the templates!

So maybe a major update instead of minor with #52 ?

[xyNNN]

Also here. Currently I've no resources to maintain this project. If you're interested I would be happy if you can support me.