Add number of routes to output

[jcoupey]

When debugging/working on instances, it's often useful to compare number of routes in solutions. Of course this info is only a jq '.routes | length' call away, but it would be nice to have it directly available as summary.routes. This would also be similar to how we report the unassigned tasks and their number in summary.

[Yash-Goyal007]

I want to work on this issue!!!!

[jcoupey]

@Yash-Goyal007 thanks for offering to help! This is mostly a matter of storing the value in the Summary object on the C++ side and adding it in the json output. You can re-use the same existing logic as with the current unassigned value.

• adding a member for number of routes in Summary would happen here;
• passing the value for Summary would happen in the Solution ctor;
• serializing the Summary object happens here.