feat: embassy-boot for rp2040

Add embassy-boot support for RP2040, with examples for the Raspberry Pi
Pico.

Co-authored-by: Mathias Koch <mk@blackbird.online>

examples/boot/application/rp/src/bin/b.rs

@@ -0,0 +1,23 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use embassy_executor::Spawner;
+use embassy_rp::gpio;
+use embassy_time::{Duration, Timer};
+use gpio::{Level, Output};
+use {defmt_rtt as _, panic_reset as _};
+
+#[embassy_executor::main]
+async fn main(_s: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    let mut led = Output::new(p.PIN_25, Level::Low);
+
+    loop {
+        led.set_high();
+        Timer::after(Duration::from_millis(100)).await;
+
+        led.set_low();
+        Timer::after(Duration::from_millis(100)).await;
+    }
+}