Expose functionality to clip HorizontalFlowBarrier class

[JoerivanEngelen]

We have quite some internal logic to clip HorizontalFlowBarrier packages away from inactive cells. However, it isn't really exposed to the user. Right now we throw validation errors when barriers are intersecting a grid. When users set strict_hfb_validation to false, the models run without error as barrier segments connecting to inactive cells are filtered away. The latter is hard to do when running models with primod (probably worthy of its own issue).

I see two ways we could do this. Either by modifying the already existing mask method, which at present doesn't do anything because vector data is independent from grid. I therefore is quite a useless method right now, just existing to keep the API consistent. The other way we could go by this is introduce a cleanup_hfb function, which takes a grid an cleans it based on that. Or both?