Add implementation of parallelized MCTS algorithm

[gabriel-trigo]

PR Description:

• This PR adds the code for running Monte Carlo Tree Search algorithm, with parallelized rollouts for speed.
• This PR adds the mcts directory inside smart_control

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.