Add initial project structure and implement async main for Pico W

src/main.rs

@@ -2,8 +2,8 @@
 #![no_main]
 
 use defmt_rtt as _;
-use panic_probe as _;
 use embassy_executor::Spawner;
+use panic_probe as _;
 
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {