Log solving profiles

[jcoupey]

The only debug info we currently have related to the local search process is a count of the number of time each operator is applied. To further analyze the current solving pattern, and the impact of further changes (e.g. #874), it would be useful to log the evolution of each of the parallelized search process:

• current solution indicators;
• time;
• triggering event, such as operator application, job addition, solution R&R etc.

We could then have a few scripts to analyze and plot the data in https://github.com/VROOM-Project/vroom-scripts/.