rp: add GPIO HIL test.

tests/rp/.cargo/config.toml

@@ -0,0 +1,20 @@
+[unstable]
+build-std = ["core"]
+build-std-features = ["panic_immediate_abort"]
+
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+#runner = "teleprobe client run --target bluepill-stm32f103c8 --elf"
+runner = "teleprobe local run --chip RP2040 --elf"
+
+rustflags = [
+  # Code-size optimizations.
+  "-Z", "trap-unreachable=no",
+  "-C", "inline-threshold=5",
+  "-C", "no-vectorize-loops",
+]
+
+[build]
+target = "thumbv6m-none-eabi"
+
+[env]
+DEFMT_LOG = "trace"