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/feature/bedlevel/bedlevel.cpp

@@ -233,7 +233,7 @@ void reset_bed_level() {
     current_position[Y_AXIS] = ry;
 
     #if ENABLED(LCD_BED_LEVELING)
-      lcd_wait_for_move = false;
+      ui.wait_for_bl_move = false;
     #endif
   }