Merge #657

657: Async usb stack r=Dirbaio a=Dirbaio

TODO

- [x] Make it work on nRF
- [x] Add a way for classes to handle their own EP0 control requests - thanks `@alexmoon!`
- [x] Handle CONTROL OUT requests with data.
- [ ] Impl AsyncRead/AsyncWrite for CDC ACM -- will do later, it's not trivial
- [x] Cleanup unwraps/asserts/panics
- [x] Cleanup logs (make everything trace/debug, not info)
- [ ] Port synopsys-usb-otg
- [ ] Port stm32-usbd
- [ ] Add more classes? HID, MSD?


Co-authored-by: Dario Nieuwenhuis <dirbaio@dirbaio.net>
Co-authored-by: alexmoon <alex.r.moon@gmail.com>

embassy-nrf/src/lib.rs

@@ -91,6 +91,7 @@ pub mod uarte;
     feature = "nrf52833",
     feature = "nrf52840"
 ))]
+#[cfg(feature = "nightly")]
 pub mod usb;
 #[cfg(not(feature = "_nrf5340"))]
 pub mod wdt;