Road Maintenance and Snow Plough should ignore vehicle restrictions

[originalfoo]

Not sure if this is already the case, but if we restrict the road service vehicles (which visit roads) it's going to cause problems.

They should be able to go anywhere, regardless of vehicle restrictions. For example, they should be able to maintain/plough bus-only roads.

They should also ignore stuff like Old Town policy, Combustion Engine Ban, Heavy Traffic Ban, etc.