Inverted position shifting idle logo (#1484)

* Inverted idle logo

Back on white background start-up logo.
Inverted idle logo with random positioning.

* Idle Logo display default true

DISPLAY_IDLE_LOGO true as burn-in screens saver, especially fo the constant heading and line

* Display Brightness added

* SSD1306toMQTT / MQTTtoSSD1306

Additional "onstate" and "brightness" setting and regular display state reporting

Docs - separate Displays section

environments.ini

@@ -772,6 +772,7 @@ build_flags =
 ;  '-DJSON_TO_LCD=true'
 ;  '-DLOG_LEVEL_LCD=LOG_LEVEL_NOTICE'
 ;  '-DDISPLAY_IDLE_LOGO=false'
+;  '-DDISPLAY_BRIGHTNESS=100'
 ;  '-DDISPLAY_METRIC=false'
 custom_description = For ESP32, Gateway using RTL_433_ESP and RadioLib
 custom_hardware = ESP32 LILYGO LoRa32 V2.1