[SERIAL] Enable SERIAL to X communication (#2068)

Add Serial as a communication layer so as to transmit data to/from serial
Enable discovery of BT sensors through serial
Add serial heartbeat

Change discovery principle for interval and intervalacts, keep them always discovered and deactivate adaptivescan when changed. Instead of removing their discovery when adaptive scan is activated

Increase JSON_MSG_BUFFER_MAX as we are now using const char* and it requires more memory for Arduino Json Deserialization

Co-authored-by: Florian <1technophile@users.noreply.github.com>

main/config_SSD1306.h

@@ -125,7 +125,7 @@
 
 extern void setupSSD1306();
 extern void loopSSD1306();
-extern void MQTTtoSSD1306(char*, JsonObject&);
+extern void XtoSSD1306(const char*, JsonObject&);
 extern String stateSSD1306Display();
 
 // Simple construct for displaying message in lcd and oled displays