Check possibility of multiple vehicles picking up people at a location

[BrunoRosendo]

also delivering people

[BrunoRosendo]

It doesn't seem to be possible in OR tools for multiple vehicles to cross the same node, check these threads:
https://stackoverflow.com/questions/59902085/is-it-possible-to-break-demands-in-several-vehicles-in-a-vrp-python-ortools
google/or-tools#1246 (comment)

The workaround is to split the nodes if their demand is too high manually, but this is suboptimal.

I will leave this implementation and see how it works with the quantum version. If the problem also happens in the quantum version, the algorithms are solving the same problem, and we can leave this refinement for later.

[BrunoRosendo]

Something like this is being implemented in #92, simply as input processing in the case where bus/metro lines have stops in common