[OTA] Enable 2 clicks OTA update / one simple MQTT command (#1485)

* [OTA] Add automatic OTA updates

This feature will enable to update the gateway with one button or a simple MQTT command.

* [CI] Enable automatic OTA for nightly development builds

And integrate the latest_version file creation into the CI

Enable to specify a particular version
and switch between dev and production builds

main/User_config.h

@@ -238,6 +238,14 @@ CAUw7C29C79Fv1C5qfPrmAESrciIxpg0X40KPMbp1ZWVbd4=
 #    ifndef MQTT_HTTPS_FW_UPDATE_USE_PASSWORD
 #      define MQTT_HTTPS_FW_UPDATE_USE_PASSWORD 1 // Set this to 0 if not using TLS connection to MQTT broker to prevent clear text passwords being sent.
 #    endif
+#    if DEVELOPMENTOTA
+#      define OTA_JSON_URL "https://github.com/1technophile/OpenMQTTGateway/raw/gh-pages/dev/firmware_build/latest_version_dev.json" //OTA url used to discover new versions of the firmware from development nightly builds
+#    else
+#      define OTA_JSON_URL "https://github.com/1technophile/OpenMQTTGateway/raw/gh-pages/firmware_build/latest_version.json" //OTA url used to discover new versions of the firmware
+#    endif
+#    define ENTITY_PICTURE   "https://github.com/1technophile/OpenMQTTGateway/raw/development/docs/img/Openmqttgateway_logo_mini_margins.png"
+#    define RELEASE_LINK_DEV "https://github.com/1technophile/OpenMQTTGateway/raw/gh-pages/dev/firmware_build/"
+#    define RELEASE_LINK     "https://github.com/1technophile/OpenMQTTGateway/releases/download/"
 #  endif
 
 #  ifndef MQTT_SECURE_SELF_SIGNED
@@ -558,7 +566,6 @@ CRGB leds2[FASTLED_IND_NUM_LEDS];
 #define subjectMQTTtoX     "/commands/#"
 #define subjectMultiGTWKey "toMQTT"
 #define subjectGTWSendKey  "MQTTto"
-#define subjectFWUpdate    "firmware_update"
 
 // key used for launching commands to the gateway
 #define restartCmd "restart"
@@ -599,6 +606,7 @@ CRGB leds2[FASTLED_IND_NUM_LEDS];
 #define InitialMQTTConnectionTimeout 10 // time estimated (s) before the board is connected to MQTT
 #define subjectSYStoMQTT             "/SYStoMQTT"
 #define subjectMQTTtoSYSset          "/commands/MQTTtoSYS/config"
+#define subjectMQTTtoSYSupdate       "/commands/MQTTtoSYS/firmware_update"
 #define TimeToResetAtStart           5000 // Time we allow the user at start for the reset command by button press
 /*-------------------DEFINE LOG LEVEL----------------------*/
 #ifndef LOG_LEVEL