Predictor/planner API

@mlerik Agents should communicate their future plans to each other. Maybe provide only API without implementation.

As a Starter Kit we should implement:

• Each agent predicts its simplified path --> Always taking action forward / or always shortest path
• All predictions of all agents are stored either as set of all visited cells (coordinates, direction, timestamp) or we build a prediction object where each cells contains a set of visiting agents, their times and their directions
• This prediction should be accessible by observation_builder and easily modified by participants of the challenge