Move traits to separate crate.

embassy-traits/src/lib.rs

@@ -0,0 +1,10 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+#![feature(generic_associated_types)]
+#![feature(const_fn)]
+#![feature(const_fn_fn_ptr_basics)]
+#![feature(const_option)]
+#![allow(incomplete_features)]
+
+pub mod flash;
+pub mod gpio;
+pub mod uart;