Introducing blackbox search configurator

[cprudhom]

This PR aims at introducing a class, namely BlackBoxConfigurator.
This should ease the way search is configured.

Here is an bunch of code:

BlackBoxConfigurator bb = BlackBoxConfigurator.init();
bb.setIntVarStrategy(Search::failureRateBasedSearch)
  .setMetaStrategy(Search::lastConflict)
  .setRestartPolicy(solver -> AbstractRestart.NO_RESTART);
bb.make(model);

Doing so, it makes possible to pre-defined some configurations and applies them in one-line call.

It can appear to be redundant with Search. However, Search does not manage restarts or nogod-recording.
Here, in one class you have everything (hopefully) you should think of when it comes to define a search strategy.

Pull request has been modified.

[ArthurGodet]

This is a great idea, it should really simplify the process of declaring searches.