Function new 

pub fn new<'a, const N_RX: usize, const N_TX: usize>(
    state: &'a mut State<N_RX, N_TX>,
) -> (Device<'a>, Runner<'a>)

Create a PPP embassy-net driver instance.

This returns two structs:

• a Device that you must pass to the embassy-net stack.
• a Runner. You must call .run() on it in a background task.