Support interactive mode in grid world

[rusu24edward]

Support an interactive mode in the grid world where the user can use the keyboard to move their agent around and battle other agents and such. Gameplan:

• [ ] Create trainer that does not train since we won't use interactive mode for training. Possibly use the debug trainer from #246 since we'll need rendering for each step in interactive mode.
• [ ] Create an interactive policy that asks for key input. This policy can map to actions which are then passed to the appropriate actor.
• [ ] This would be particularly useful for playing against trained agents. So we could add an abmarl interact command or we could add it as an argument for the visualize command.

Should be done after #246

[rusu24edward]

It looks like the best way to do this is using the cmd module