Provide capacities per vehicle at each location in output

[daniel-j-h]

We should output the capacity each vehicle has before / after servicing a location.

Use-case: being able to tell the vehicle's load at a specific time and place.

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Implementation:

• When an assignment could be found: for each vehicle walk over all location indices in the route
• For each location index store the accumulated capacity domain at this location for the vehicle

const auto* loadVar = capacityDimension.CumulVar(index);
assignment->Value(loadVar)