Add support for contextual path arguments

Please find the attached patch.

I've been testing the patch in real life and I found an issue, this new patch prevents some issues in when you need to save several paths for same controller.

Let's try to resolve this for the upcoming 2.1.0 release.

The patch needs to be rerolled against the 2.0.x branch.

@alvar0hurtad0 or @biancaradu27 could you perhaps reroll this against 2.0.x or even better turn this into a MR against it?
Based on the results we should eventually consider this for 2.2.0 to not block 2.1.0 here? Seems it's not that important for the community (not much activity)?