Add additional naming strategy - option to replace files on upload

[simonvomeyser]

Hey-ho dear maintainers!

Really like this package, thank you for your work 👍

I use it a lot to give customers the possibility to change images on otherwise static sites.

I created a naming strategy for replacing images when uploaded with the same name and added it to the repo. I also updated the docs accordingly.

Are you generally interested in this functionality in your package? I would really like to extend on the "replace file" idea to a later date then.

If not, no biggie, just thought I'd show you some appreciation :)

Keep up the good work and greetings from Germany
Simon vom Eyser