button_checker function

[lilibp]

Purpose:

The button_checker function toggles the button state between "up" and "down" based on the input.

Inputs:

• press (bool): Current button press state.

Outputs:

• button_state (bool): The updated button state.

Notes:

Ensure proper state toggling for all input scenarios.

[lilibp]

I ended up writing this code's function, but Yann will be tasked with writing the unittest for it.