Ubl delta fixes and improvements (#6941)

* Change all direct changes of ubl.state.active to
  set_bed_leveling_enabled() which handles apply/unapply
  leveling to maintain current_position consistency.

Fix invalidation of UBL mesh to invalid unreachable
  mesh points as well (delta corners).

Fix UBL_DELTA unapply_leveling logic and when
it gets applied, including fade_height changes.

Add optional M114 D for detailed position information,
disabled from compilation by default (M114_DETAIL).

* UBL_DELTA raw and inline kinematics

* UBL planner fall through fix

* consistent variable names

* Cleanup orphaned code and whitespace changes.
Use _O2.

* compile warnings cleanup

* Remove redundant #ifdef condition

Marlin/G26_Mesh_Validation_Tool.cpp

@@ -718,7 +718,7 @@
     /**
      * Wait until all parameters are verified before altering the state!
      */
-    state.active = !parser.seen('D');
+    set_bed_leveling_enabled(!parser.seen('D'));
 
     return UBL_OK;
   }
@@ -734,7 +734,7 @@
    * wait for them to get up to temperature.
    */
   bool unified_bed_leveling::turn_on_heaters() {
-    millis_t next;
+    millis_t next = millis() + 5000UL;
     #if HAS_TEMP_BED
       #if ENABLED(ULTRA_LCD)
         if (g26_bed_temp > 25) {
@@ -743,7 +743,6 @@
       #endif
           has_control_of_lcd_panel = true;
           thermalManager.setTargetBed(g26_bed_temp);
-          next = millis() + 5000UL;
           while (abs(thermalManager.degBed() - g26_bed_temp) > 3) {
             if (ubl_lcd_clicked()) return exit_from_g26();
             if (PENDING(millis(), next)) {