[environment, learning] Move logic from `environments.HarvestEnv` to `board.HarvestGame`

[quinn-dougherty]

• move time property from environments.HarvestEnv to board.HarvestGame
• move lines 32-40 of environments.HarvestEnv.step to board.HarvestGame.step, (note the plural)

  def step(self, actions: Dict[AgentID, int]) -> Dict[AgentID, float]: 
   """takes actions dict and returns rewards dict"""

[quinn-dougherty]

note: after this issue is done, train to see if greed/exhaustion happens.