build: clean up the mess of ifdefs from platform into a scons-configured hal

src/BootOptions.h

@@ -1,5 +1,6 @@
 #pragma once
 #include <Arduino.h>
+#include "Hal.h"
 
 struct BootOptions {
     static void initPins();
@@ -7,7 +8,6 @@ struct BootOptions {
     BootOptions();
 
     void waitForRelease();
-    void forceSafeMode();
 
     bool isSetup = false;
     bool isSerial = false;