Generate warnings if Pico SDDIO init called

Warn the user that the Pico SDK STDIO calls (stdio_init_all, stdio_usb_init,
stdio_uart_init) are not supported or needed at compile time.  See multiple
issues #1433 #1347 #1273 #1251 and others.

cores/rp2040/Arduino.h

@@ -105,6 +105,14 @@ extern bool __isFreeRTOS;
 #define PGM_VOID_P void *
 #endif
 
+// Warn users trying to use Pico SDK's STDIO implementation
+#undef stdio_uart_init
+#define stdio_uart_init() static_assert(0, "stdio_init_all, stdio_usb_init, and stdio_uart_init is not supported or needed. Either use Serial.printf() or set the debug port in the IDE to Serial/1/2 and use printf().  See https://github.com/earlephilhower/arduino-pico/issues/1433#issuecomment-1540354673 and https://github.com/earlephilhower/arduino-pico/issues/1433#issuecomment-1546783109")
+#undef stdio_init_all
+#define stdio_init_all() stdio_uart_init()
+#undef stdio_usb_init
+#define stdio_usb_init() stdio_uart_init()
+
 #ifdef __cplusplus
 
 // emptyString is an ESP-ism, a constant string with ""