Add get_waypoints_state method to the simulator and visualize all waypoints when recording birdviews

[lioutasb]

No description provided.

[adscib]

Can you explain how this works with instances of NPCWrapper? Do you return waypoints for all agents, including the hidden ones? If so, what's the mechanism for matching them to the exposed agents?

[lioutasb]

Waypoints are defined at the creation of the base simulator object. This means that waypoints (appropriately masked) must be given for all possible agents and agent types. The methods that return waypoint states, masks, etc follow the implementation and interface similar to the get_state() method on the various wrappers that restrict the agent dimension based on which agents are exposed. Similarly for the homogeneous wrapper that concatenates everything.