Full support for Athom WLED Music Controller

- athom_music_esp32_4MB_M bin
- show flashsize in info tab and /getflash
- support of their ir-remote (24-key music)

Not supported yet
- mac addres in AP name (need to experiment with WLED_AP_SSID_UNIQUE)

wled00/json.cpp

@@ -892,6 +892,7 @@ void serializeInfo(JsonObject root)
   #endif
   root[F("lwip")] = 0; //deprecated
   root[F("totalheap")] = ESP.getHeapSize(); //WLEDMM
+  root[F("getflash")] = ESP.getFlashChipSize(); //WLEDMM and Athom
   #else
   root[F("arch")] = "esp8266";
   root[F("core")] = ESP.getCoreVersion();