move bluetooth code into something that is architecture specific...

because the ESP32 implementation will be different from NRF52
to make this possible I needed to decouple knowlege about bluetooth from
our mesh service.  Instead mesh service now uses the Obserable pattern
to let any interested consumer get notified of important mesh changes
(currently that is only bluetooth, but really we should do the same
thing for decoupling the GUI 'app' from the mesh service)

@girtsf would you mind reviewing my Observer changes? I haven't written
C++ code in a long time ;-)

src/sleep.cpp

@@ -1,7 +1,5 @@
 #include "sleep.h"
-#include "BluetoothUtil.h"
 #include "GPS.h"
-#include "MeshBluetoothService.h"
 #include "MeshRadio.h"
 #include "MeshService.h"
 #include "NodeDB.h"
@@ -11,9 +9,14 @@
 #include "esp_pm.h"
 #include "main.h"
 #include "rom/rtc.h"
+#include "target_specific.h"
 #include <Wire.h>
 #include <driver/rtc_io.h>
 
+#ifndef NO_ESP32
+#include "BluetoothUtil.h"
+#endif
+
 #ifdef TBEAM_V10
 #include "axp20x.h"
 extern AXP20X_Class axp;
@@ -105,7 +108,9 @@ void doDeepSleep(uint64_t msecToWake)
     // not using wifi yet, but once we are this is needed to shutoff the radio hw
     // esp_wifi_stop();
 
+#ifndef NO_ESP32
     BLEDevice::deinit(false); // We are required to shutdown bluetooth before deep or light sleep
+#endif
 
     screen.setOn(false); // datasheet says this will draw only 10ua