Implement a method to invalidate the cache

As discussed in #217 we need a method / mechanism to invalidate the cache for specific paths.

This is needed because, if the user move / delete a file, and it is still in the cache, the library will continue to 'think' that the file is still in the old location. Leading to unexpected behaviors.

This mechanism is needed in the `mv` and `rm_file` method.

Start by reading the discussion in issue #217 and the existing mv and rm_file methods. Trace how cached paths are stored and used, then define the invalidation behavior for moved and deleted files. Done means those methods no longer leave stale entries that make the library report files at their old locations.

Rédigé par le modèle d'indexation à partir du texte de l'issue.