SHT usermod MoonModules upgrade

Use MM specific features in SHT usermod:

* Join global I2C bus with pinManager.joinWire()
* allow to compile without MQTT
* use extended Usermod class features
* prevent sensor starvation when running with > 600 LEDs

wled00/usermods_list.cpp

@@ -374,7 +374,7 @@ void registerUsermods()
   #endif
 
   #ifdef USERMOD_SHT
-  usermods.add(new ShtUsermod());
+  usermods.add(new ShtUsermod("SHT-Sensor", false));
   #endif
 
   //WLEDMM ARTIFX