Remove uses of gamepad

[dhalbert]

gamepad is being replaced by keypad in CircuitPython 7.0.0.

It is used for were_pressed() in the CP library (and is also mentioned in conf.py). were_pressed() could be implemented using keypad, but it would be easier to change the API slightly to make the reimplementation simpler, so we don't need to simulate gamepads latching behavior by remembering states. That means there might be guide examples to change.

We should talk about how to transition the CP API in that case.

[dhalbert]

I looked at how gamepad was replaced by @deshipu, and thought about this some more, and I think we can just drain the event queue: it's not so hard.