[feat] Change the type of the ball

[EnderXie23]

Currently, there is only one type of ball in the game (namely, the stone ball). We may add more types of balls like wooden/paper ones to make the game more interesting. The mass, friction and other properties shall also be altered to address this change.

[EnderXie23]

I tried to implement this feature but it seems that we're unable to change the texture of the ball during game. The physics of the different balls are already implemented in this code, together with a 1-sec built-in cd.