Adapt get_intersections function for work_schedules

[anisometropie]

Actually, I have some doubts as to whether get_intersections is the function we need.

There's a slight difference between the train schedule projection and the work schedule projection:

• A train schedule path is linear, a work schedule track ranges are not
• A PathProjection required unique tranck sections, which might not be the case for work schedule track ranges

I think we could adapt the get_intersections function to make it work in the general case (work schedule). This could be done in a later PR.

Originally posted by @flomonster in #8794 (comment)