Display alerts (#4170)

* Move static functions into Screen.h, show compass during calibration

* Move to _fontHeight macro to avoid collision

* Move some alert functions to new alert handler

* Catch missed reboot code

* ESP32 fixes

* Bump esp8266-oled-ssd1306

* Fixes for when a device has no screen

* Use new startAlert(char*) helper class

* Add EINK bits back to alert handling

* Add noop class for no-display devices

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Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/main.cpp

@@ -930,7 +930,7 @@ void setup()
         nodeDB->saveToDisk(SEGMENT_CONFIG);
         if (!rIf->reconfigure()) {
             LOG_WARN("Reconfigure failed, rebooting\n");
-            screen->startRebootScreen();
+            screen->startAlert("Rebooting...");
             rebootAtMsec = millis() + 5000;
         }
     }