[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/config_mqttDiscovery.h

@@ -268,4 +268,10 @@ const char* availableHASSUnits[] = {"W",
                                     "mm/h",
                                     "cm"};
 
+// Define the command used to update through OTA depending if we want to update from dev nightly or latest release
+#if DEVELOPMENTOTA
+#  define LATEST_OR_DEV "{\"version\":\"dev\"}"
+#else
+#  define LATEST_OR_DEV "{\"version\":\"latest\"}"
+#endif
 #endif