map joystick and buttons to keyboard keys

[loothero]

To allow joystick and buttons to be used within the Web3 games, we need to map the joystick and buttons to keyboard keys. The joystick should map to up, down, left, right and the buttons should map to any reasonable set of keys.

We'll standardize on the mapping of buttons to keyboard keys such that if a game wants to support arcade mode, it'll simply need to update client to be playable using arrow keys and 6 keyboard buttons.