lots of changes:

* preflightSleep, notifySleep, notifyDeepSleep now allow arbitrary
drivers/devices/software to register for sleep notification.
* Use the proceeding to clean up MeshRadio - now the mesh radio is more
like an independent driver that doesn't care so much about other systems
* clean up MeshService so that it can work with zero MeshRadios added.
This is a prelude to supporting boards with multiple interfaces (wifi,
extra LORA radios etc) and allows development/testing in sim with a bare
ESP32 board
* Remove remaining ESP32 dependencies from the bare simulation target
this allows running on anything that implements the arduino API

src/error.h

@@ -1,7 +1,7 @@
 #pragma once
 
 /// Error codes for critical error
-enum CriticalErrorCode { NoError, ErrTxWatchdog, ErrSleepEnterWait };
+enum CriticalErrorCode { NoError, ErrTxWatchdog, ErrSleepEnterWait, ErrNoRadio };
 
 /// Record an error that should be reported via analytics
 void recordCriticalError(CriticalErrorCode code, uint32_t address = 0);