move most interrupt methods to InterruptExt extension trait. Fixes #35

embassy-nrf/src/buffered_uarte.rs

@@ -10,6 +10,7 @@ use core::ops::Deref;
 use core::pin::Pin;
 use core::sync::atomic::{compiler_fence, Ordering};
 use core::task::{Context, Poll};
+use embassy::interrupt::InterruptExt;
 use embassy::io::{AsyncBufRead, AsyncWrite, Result};
 use embassy::util::WakerRegistration;
 use embedded_hal::digital::v2::OutputPin;