Cleanup interrupt package naming. Fixes #40

The `interrupt` package previously tried to be drop-in compatible with the
`interrupt` package from PACs. THis meant that there was both a PAC-style enum
value `UARTE0` and an embassy-style owned `UARTE0Interrupt` type. This made
things VERY confusing.

This drops compatibility with the PAC, improving the names for embassy interrupts.

embassy-nrf/src/lib.rs

@@ -60,5 +60,3 @@ pub mod interrupt;
 pub mod qspi;
 pub mod rtc;
 pub mod uarte;
-
-pub use cortex_m_rt::interrupt;