Encapsulate common display code in a singleton (#12395)

* Encapsulate common LCD code in a singleton
* Depend more UBL code on UBL_DEVEL_DEBUGGING
  - Since most users don't need the debugging on at all times, this helps reduce the default build size for UBL by over 2K, a little closer to fitting on 128K boards.

Marlin/src/gcode/motion/G4.cpp

@@ -38,7 +38,7 @@ void GcodeSuite::G4() {
     SERIAL_ECHOLNPGM(MSG_Z_MOVE_COMP);
   #endif
 
-  if (!lcd_hasstatus()) LCD_MESSAGEPGM(MSG_DWELL);
+  if (!ui.hasstatus()) LCD_MESSAGEPGM(MSG_DWELL);
 
   dwell(dwell_ms);
 }