Raspberry Pi Pico target (with sparkfun lora hat) does compile but needs further work.

Also contains a small fix to make PRIVATE_HW targets build again for nRF52 architectures

src/rp2040/architecture.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#define ARCH_RP2040
+
+#if defined(PRIVATE_HW)
+    #define HW_VENDOR HardwareModel_PRIVATE_HW
+#endif