Candy element

[gaorkl]

I want to create a new element named Candy.
This element should be activated upon contact with an agent.
It should be removed from the playground and provide a reward to the agent.

I also want tests that can test if it is working properly. They should be put in tests/test_components/test_contact_elements.py
There are examples of similar behaviors in tests/mock_interactives.py

Pick an image for the candy from the arcade resources.